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Sample records for cadmium-containing crystals based

  1. Application prospects of cadmium-containing crystals based on tungstates and double tungstates

    CERN Document Server

    Nagornaya, L; Apanasenko, A; Tupitsyna, I; Chernikov, V; Vostretsov, V

    2002-01-01

    Tungstate and double tungstate crystals of high scintillation efficiency and detectors based on them are applied widely in the medical imaging and radiation monitoring because of their high sensitivity to the ionizing radiation, small radiation length, high radiation hardness, low afterglow level. In this work a possibility to broaden the application field of CWO crystals have been investigated by improvement of their spectrometric quality and decreasing of their afterglow level. CWO crystals with improved characteristics have been obtained (resolution for sup 1 sup 3 sup 7 Cs <8%, afterglow <0.02% after 20 ms). A possibility is considered to use these crystals for spectrometry of thermal and resonance neutrons, which is possible due to the presence of nuclei with large cross-section for these neutrons in the crystal lattice. Compounds of a new type based on Cd, La-containing double tungstates doped with rare earth elements have been synthesized, and their luminescent characteristics have been studied. ...

  2. Cytotoxicity of cadmium-containing quantum dots based on a study using a microfluidic chip

    Science.gov (United States)

    Zheng, Xiannuo; Tian, Jing; Weng, Lixing; Wu, Lei; Jin, Qinghui; Zhao, Jianlong; Wang, Lianhui

    2012-02-01

    There is a lack of reliable nanotoxicity assays available for monitoring and quantifying multiple cellular events in cultured cells. In this study, we used a microfluidic chip to systematically investigate the cytotoxicity of three kinds of well-characterized cadmium-containing quantum dots (QDs) with the same core but different shell structures, including CdTe core QDs, CdTe/CdS core-shell QDs, and CdTe/CdS/ZnS core-shell-shell QDs, in HEK293 cells. Using the microfluidic chip combined with fluorescence microscopy, multiple QD-induced cellular events including cell morphology, viability, proliferation, and QD uptake were simultaneously analysed. The three kinds of QDs showed significantly different cytotoxicities. The CdTe QDs, which are highly toxic to HEK293 cells, resulted in remarkable cellular and nuclear morphological changes, a dose-dependent decrease in cell viability, and strong inhibition of cell proliferation; the CdTe/CdS QDs were moderately toxic but did not significantly affect the proliferation of HEK293 cells; while the CdTe/CdS/ZnS QDs had no detectable influence on cytotoxicity with respect to cell morphology, viability, and proliferation. Our data indicated that QD cytotoxicity was closely related to their surface structures and specific physicochemical properties. This study also demonstrated that the microfluidic chip could serve as a powerful tool to systematically evaluate the cytotoxicity of nanoparticles in multiple cellular events.

  3. Protein Crystal Based Nanomaterials

    Science.gov (United States)

    Bell, Jeffrey A.; VanRoey, Patrick

    2001-01-01

    This is the final report on a NASA Grant. It concerns a description of work done, which includes: (1) Protein crystals cross-linked to form fibers; (2) Engineering of protein to favor crystallization; (3) Better knowledge-based potentials for protein-protein contacts; (4) Simulation of protein crystallization.

  4. Diamond based photonic crystal microcavities.

    Science.gov (United States)

    Tomljenovic-Hanic, S; Steel, M J; de Sterke, C Martijn; Salzman, J

    2006-04-17

    Diamond based technologies offer a material platform for the implementation of qubits for quantum computing. The photonic crystal architecture provides the route for a scalable and controllable implementation of high quality factor (Q) nanocavities, operating in the strong coupling regime for cavity quantum electrodynamics. Here we compute the photonic band structures and quality factors of microcavities in photonic crystal slabs in diamond, and compare the results with those of the more commonly-used silicon platform. We find that, in spite of the lower index contrast, diamond based photonic crystal microcavities can exhibit quality factors of Q=3.0x10(4), sufficient for proof of principle demonstrations in the quantum regime. PMID:19516502

  5. Liquid Crystal Cells Based on Photovoltaic Substrates

    Science.gov (United States)

    Lucchetti, L.; Kushnir, K.; Zaltron, A.; Simoni, F.

    2016-02-01

    Liquid crystal cells with LiNbO3:Fe crystals as substrates, are described. The photovoltaic field generated by the substrates is able to reorient the liquid crystal director thus giving rise to a phase shift on the light propagating through the cell, as in liquid crystal light valves. The process does not require the application of an external electric field, thus being potentially useful for applications requiring a high degree of compactness. An efficient optical switch with a high transmission contrast, based on the described optically-induced electric field, is also proposed.

  6. Monitoring LSO/LYSO Crystal Based Calorimeters

    Science.gov (United States)

    Yang, Fan; Zhang, Liyuan; Zhu, Ren-Yuan

    2015-02-01

    Precision light monitoring is important for keeping excellent energy resolution promised by LSO/LYSO crystals in severe radiation environment. In this paper, we report an investigation on the wavelength choice for monitoring LYSO crystal based calorimeters. Gamma-ray induced absorption and light output loss were measured for 20 cm long crystals from five different vendors. Monitoring sensitivity and divergence between crystals from different vendors were investigated. The pros and cons of two monitoring approaches using emission and excitation light and their practical implementation for a LYSO/W Shashlik test beam matrix are discussed.

  7. Photonic crystal fiber based antibody detection

    DEFF Research Database (Denmark)

    Duval, A; Lhoutellier, M; Jensen, J B;

    2004-01-01

    An original approach for detecting labeled antibodies based on strong penetration photonic crystal fibers is introduced. The target antibody is immobilized inside the air-holes of a photonic crystal fiber and the detection is realized by the means of evanescent-wave fluorescence spectroscopy...... and the use of a transversal illumination setup....

  8. Polymer-based photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Edrington, A.C.; Urbas, A.M.; Fink, Y.; Thomas, E.L. [Massachusetts Inst. of Tech., Cambridge (United States). Dept. of Materials Science and Engineering; DeRege, P. [Firmenich, Inc., Port Newark, NJ (United States); Chen, C.X.; Swager, T.M. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Chemistry; Hadjichristidis, N. [Athens Univ. (Greece). Dept. of Chemistry; Xenidou, M.; Fetters, L.J. [ExxonMobil Research Corp., Annandale, NJ (United States); Joannopoulos, J.D. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Physics

    2001-03-16

    The development of polymers as photonic crystals is highlighted, placing special emphasis on self-assembled block copolymers. 1D self-assembled multilayers as well as 2D and 3D self-assembled structures are examined, then intricate block polymer structures such as that shown in the Figure are discussed as are birefringent multilayer and elastomeric films. (orig.)

  9. Crystal bases and quiver varieties (Geometric construction of crystal bases II)

    OpenAIRE

    Saito, Yoshihisa

    2001-01-01

    We give a crystal structure on the set of all irreducible components of Lagrangian subvarieties of quiver varieties. One con show that, as a crystal, it is isomorphic to the crystal base of an irreducible highest weight representation of a quantized universal enveloping algebra.

  10. Fluorous-based carbohydrate quartz crystal microbalance.

    Science.gov (United States)

    Chen, Lei; Sun, Pengfei; Chen, Guosong

    2015-03-20

    Fluorous chemistry has brought many applications from catalysis to separation science, from supramolecular materials to analytical chemistry. However, fluorous-based quartz crystal microbalance (QCM) has not been reported so far. In the current paper, fluorous interaction has been firstly utilized in QCM, and carbohydrate-protein interaction and carbohydrate-carbohydrate interaction have been detected afterward. PMID:25541017

  11. Photonic Crystal Sensors Based on Porous Silicon

    Directory of Open Access Journals (Sweden)

    Claudia Pacholski

    2013-04-01

    Full Text Available Porous silicon has been established as an excellent sensing platform for the optical detection of hazardous chemicals and biomolecular interactions such as DNA hybridization, antigen/antibody binding, and enzymatic reactions. Its porous nature provides a high surface area within a small volume, which can be easily controlled by changing the pore sizes. As the porosity and consequently the refractive index of an etched porous silicon layer depends on the electrochemial etching conditions photonic crystals composed of multilayered porous silicon films with well-resolved and narrow optical reflectivity features can easily be obtained. The prominent optical response of the photonic crystal decreases the detection limit and therefore increases the sensitivity of porous silicon sensors in comparison to sensors utilizing Fabry-Pérot based optical transduction. Development of porous silicon photonic crystal sensors which allow for the detection of analytes by the naked eye using a simple color change or the fabrication of stacked porous silicon photonic crystals showing two distinct optical features which can be utilized for the discrimination of analytes emphasize its high application potential.

  12. Crystallization kinetics of Fe based amorphous alloy

    Science.gov (United States)

    Shanker Rao, T.; Lilly Shanker Rao, T.

    2015-02-01

    Differential Scanning Calorimetry(DSC) experimental data under non-isothermal conditions for Fe based Metglas 2605SA1 (wt% Fe=85-95, Si=5-10, B=1-5) metallic glass ribbons are reported and discussed. The DSC Scans performed at different heating rates showed two step crystallization processes and are interpreted in terms of different models like Kissinger, Ozawa, Boswell, Augis & Bennett and Gao & Wang. From the heating rate dependence of the onset temperature (To) and the crystallization peak temperature (Tp), the kinetic triplet, activation energy of crystallization (E), Avrami exponent (n) and the frequency factor (A) are determined. The determined E for peak I is 354.5 ± 2.5 kJ/mol and for the peak II is 348.2 ± 2.2 kJ/mol, respectively. The frequency factor for peak I is 1.1 × 1023sec-1 and for peak II is 6.1 × 1020sec-1.

  13. Biaxial crystal-based optical tweezers

    DEFF Research Database (Denmark)

    Angelsky, Oleg V.; Maksimyak, Andrew P.; Maksimyak, Peter P.;

    2010-01-01

    We suggest an optical tweezer setup based on an optically biaxial crystal. To control movements of opaque particles, we use shifts. The results of experimental studies are reported which are concerned with this laser tweezer setup. We demonstrate a movement of microparticles of toner using a sing...... a singular-optical trap, rotation of particles due to orbital angular momentum of the field, and converging or diverging of two different traps when changing transmission plane of polariser at the input of our polarisation interferometer....

  14. Fork gratings based on ferroelectric liquid crystals.

    Science.gov (United States)

    Ma, Y; Wei, B Y; Shi, L Y; Srivastava, A K; Chigrinov, V G; Kwok, H-S; Hu, W; Lu, Y Q

    2016-03-21

    In this article, we disclose a fork grating (FG) based on the photo-aligned ferroelectric liquid crystal (FLC). The Digital Micro-mirror Device based system is used as a dynamic photomask to generated different holograms. Because of controlled anchoring energy, the photo alignment process offers optimal conditions for the multi-domain FLC alignment. Two different electro-optical modes namely DIFF/TRANS and DIFF/OFF switchable modes have been proposed where the diffraction can be switched either to no diffraction or to a completely black state, respectively. The FLC FG shows high diffraction efficiency and fast response time of 50µs that is relatively faster than existing technologies. Thus, the FLC FG may pave a good foundation toward optical vertices generation and manipulation that could find applications in a variety of devices. PMID:27136779

  15. Ionizing particle detection based on phononic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Aly, Arafa H., E-mail: arafa16@yahoo.com, E-mail: arafa.hussien@science.bsu.edu.eg; Mehaney, Ahmed; Eissa, Mostafa F. [Physics Department, Faculty of Science, Beni-Suef University, Beni-Suef (Egypt)

    2015-08-14

    Most conventional radiation detectors are based on electronic or photon collections. In this work, we introduce a new and novel type of ionizing particle detector based on phonon collection. Helium ion radiation treats tumors with better precision. There are nine known isotopes of helium, but only helium-3 and helium-4 are stable. Helium-4 is formed in fusion reactor technology and in enormous quantities during Big Bang nucleo-synthesis. In this study, we introduce a technique for helium-4 ion detection (sensing) based on the innovative properties of the new composite materials known as phononic crystals (PnCs). PnCs can provide an easy and cheap technique for ion detection compared with conventional methods. PnC structures commonly consist of a periodic array of two or more materials with different elastic properties. The two materials are polymethyl-methacrylate and polyethylene polymers. The calculations showed that the energies lost to target phonons are maximized at 1 keV helium-4 ion energy. There is a correlation between the total phonon energies and the transmittance of PnC structures. The maximum transmission for phonons due to the passage of helium-4 ions was found in the case of making polyethylene as a first layer in the PnC structure. Therefore, the concept of ion detection based on PnC structure is achievable.

  16. Ionizing particle detection based on phononic crystals

    Science.gov (United States)

    Aly, Arafa H.; Mehaney, Ahmed; Eissa, Mostafa F.

    2015-08-01

    Most conventional radiation detectors are based on electronic or photon collections. In this work, we introduce a new and novel type of ionizing particle detector based on phonon collection. Helium ion radiation treats tumors with better precision. There are nine known isotopes of helium, but only helium-3 and helium-4 are stable. Helium-4 is formed in fusion reactor technology and in enormous quantities during Big Bang nucleo-synthesis. In this study, we introduce a technique for helium-4 ion detection (sensing) based on the innovative properties of the new composite materials known as phononic crystals (PnCs). PnCs can provide an easy and cheap technique for ion detection compared with conventional methods. PnC structures commonly consist of a periodic array of two or more materials with different elastic properties. The two materials are polymethyl-methacrylate and polyethylene polymers. The calculations showed that the energies lost to target phonons are maximized at 1 keV helium-4 ion energy. There is a correlation between the total phonon energies and the transmittance of PnC structures. The maximum transmission for phonons due to the passage of helium-4 ions was found in the case of making polyethylene as a first layer in the PnC structure. Therefore, the concept of ion detection based on PnC structure is achievable.

  17. Crystallization of zirconia based thin films.

    Science.gov (United States)

    Stender, D; Frison, R; Conder, K; Rupp, J L M; Scherrer, B; Martynczuk, J M; Gauckler, L J; Schneider, C W; Lippert, T; Wokaun, A

    2015-07-28

    The crystallization kinetics of amorphous 3 and 8 mol% yttria stabilized zirconia (3YSZ and 8YSZ) thin films grown by pulsed laser deposition (PLD), spray pyrolysis and dc-magnetron sputtering are explored. The deposited films were heat treated up to 1000 °C ex situ and in situ in an X-ray diffractometer. A minimum temperature of 275 °C was determined at which as-deposited amorphous PLD grown 3YSZ films fully crystallize within five hours. Above 325 °C these films transform nearly instantaneously with a high degree of micro-strain when crystallized below 500 °C. In these films the t'' phase crystallizes which transforms at T > 600 °C to the t' phase upon relaxation of the micro-strain. Furthermore, the crystallization of 8YSZ thin films grown by PLD, spray pyrolysis and dc-sputtering are characterized by in situ XRD measurements. At a constant heating rate of 2.4 K min(-1) crystallization is accomplished after reaching 800 °C, while PLD grown thin films were completely crystallized already at ca. 300 °C. PMID:26119755

  18. Effect of Crystal Orientation on Fatigue Failure of Single Crystal Nickel Base Turbine Blade Superalloys

    Science.gov (United States)

    Arakere, N. K.; Swanson, G.

    2002-01-01

    High cycle fatigue (HCF) induced failures in aircraft gas turbine and rocket engine turbopump blades is a pervasive problem. Single crystal nickel turbine blades are being utilized in rocket engine turbopumps and jet engines throughout industry because of their superior creep, stress rupture, melt resistance, and thermomechanical fatigue capabilities over polycrystalline alloys. Currently the most widely used single crystal turbine blade superalloys are PWA 1480/1493, PWA 1484, RENE' N-5 and CMSX-4. These alloys play an important role in commercial, military and space propulsion systems. Single crystal materials have highly orthotropic properties making the position of the crystal lattice relative to the part geometry a significant factor in the overall analysis. The failure modes of single crystal turbine blades are complicated to predict due to the material orthotropy and variations in crystal orientations. Fatigue life estimation of single crystal turbine blades represents an important aspect of durability assessment. It is therefore of practical interest to develop effective fatigue failure criteria for single crystal nickel alloys and to investigate the effects of variation of primary and secondary crystal orientation on fatigue life. A fatigue failure criterion based on the maximum shear stress amplitude /Delta(sub tau)(sub max))] on the 24 octahedral and 6 cube slip systems, is presented for single crystal nickel superalloys (FCC crystal). This criterion reduces the scatter in uniaxial LCF test data considerably for PWA 1493 at 1200 F in air. Additionally, single crystal turbine blades used in the alternate advanced high-pressure fuel turbopump (AHPFTP/AT) are modeled using a large-scale three-dimensional finite element model. This finite element model is capable of accounting for material orthotrophy and variation in primary and secondary crystal orientation. Effects of variation in crystal orientation on blade stress response are studied based on 297

  19. Hyperbolic polaritonic crystals based on nanostructured nanorod metamaterials.

    Science.gov (United States)

    Dickson, Wayne; Beckett, Stephen; McClatchey, Christina; Murphy, Antony; O'Connor, Daniel; Wurtz, Gregory A; Pollard, Robert; Zayats, Anatoly V

    2015-10-21

    Surface plasmon polaritons usually exist on a few suitable plasmonic materials; however, nanostructured plasmonic metamaterials allow a much broader range of optical properties to be designed. Here, bottom-up and top-down nanostructuring are combined, creating hyperbolic metamaterial-based photonic crystals termed hyperbolic polaritonic crystals, allowing free-space access to the high spatial frequency modes supported by these metamaterials.

  20. Effect of Crystal Orientation on Analysis of Single-Crystal, Nickel-Based Turbine Blade Superalloys

    Science.gov (United States)

    Swanson, G. R.; Arakere, N. K.

    2000-01-01

    High-cycle fatigue-induced failures in turbine and turbopump blades is a pervasive problem. Single-crystal nickel turbine blades are used because of their superior creep, stress rupture, melt resistance, and thermomechanical fatigue capabilities. Single-crystal materials have highly orthotropic properties making the position of the crystal lattice relative to the part geometry a significant and complicating factor. A fatigue failure criterion based on the maximum shear stress amplitude on the 24 octahedral and 6 cube slip systems is presented for single-crystal nickel superalloys (FCC crystal). This criterion greatly reduces the scatter in uniaxial fatigue data for PWA 1493 at 1,200 F in air. Additionally, single-crystal turbine blades used in the Space Shuttle main engine high pressure fuel turbopump/alternate turbopump are modeled using a three-dimensional finite element (FE) model. This model accounts for material orthotrophy and crystal orientation. Fatigue life of the blade tip is computed using FE stress results and the failure criterion that was developed. Stress analysis results in the blade attachment region are also presented. Results demonstrate that control of crystallographic orientation has the potential to significantly increase a component's resistance to fatigue crack growth without adding additional weight or cost.

  1. Optical limiter based on two-dimensional nonlinear photonic crystals

    Science.gov (United States)

    Belabbas, Amirouche; Lazoul, Mohamed

    2016-04-01

    The aim behind this work is to investigate the capabilities of nonlinear photonic crystals to achieve ultra-fast optical limiters based on third order nonlinear effects. The purpose is to combine the actions of nonlinear effects with the properties of photonic crystals in order to activate the photonic band according to the magnitude of the nonlinear effects, themselves a function of incident laser power. We are interested in designing an optical limiter based nonlinear photonic crystal operating around 1064 nm and its second harmonic at 532 nm. Indeed, a very powerful solid-state laser that can blind or destroy optical sensors and is widely available and easy to handle. In this work, we perform design and optimization by numerical simulations to determine the better structure for the nonlinear photonic crystal to achieve compact and efficient integrated optical limiter. The approach consists to analyze the band structures in Kerr-nonlinear two-dimensional photonic crystals as a function of the optical intensity. We confirm that these bands are dynamically red-shifted with regard to the bands observed in linear photonic crystals or in the case of weak nonlinear effects. The implemented approach will help to understand such phenomena as intensitydriven optical limiting with Kerr-nonlinear photonic crystals.

  2. Continuous preparation of polymer coated drug crystals by solid hollow fiber membrane-based cooling crystallization.

    Science.gov (United States)

    Chen, Dengyue; Singh, Dhananjay; Sirkar, Kamalesh K; Pfeffer, Robert

    2016-02-29

    A facile way to continuously coat drug crystals with a polymer is needed in controlled drug release. Conventional polymer coating methods have disadvantages: high energy consumption, low productivity, batch processing. A novel method for continuous polymer coating of drug crystals based on solid hollow fiber cooling crystallization (SHFCC) is introduced here. The drug acting as the host particle and the polymer for coating are Griseofulvin (GF) and Eudragit RL100, respectively. The polymer's cloud point temperature in its acetone solution was determined by UV spectrophotometry. An acetone solution of the polymer containing the drug in solution as well as undissolved drug crystals in suspension were pumped through the tube side of the SHFCC device; a cold liquid was circulated in the shell side to rapidly cool down the feed solution-suspension in the hollow-fiber lumen. The polymer precipitated from the solution and coated the suspended crystals due to rapid temperature reduction and heterogeneous nucleation; crystals formed from the solution were also coated by the polymer. Characterizations by scanning electron microscopy, thermogravimetric analysis, laser diffraction spectroscopy, X-ray diffraction, Raman spectroscopy, and dissolution tests show that a uniformly coated, free-flowing drug/product can be obtained under appropriate operating conditions without losing the drug's pharmaceutical properties and controlled release characteristics. PMID:26772536

  3. Heterocyclic benzoxazole-based liquid crystals: Synthesis and mesomorphic properties

    Institute of Scientific and Technical Information of China (English)

    Sie Tiong Ha; Kok Leei Foo; Ramesh T. Subramaniam; Masato M. Ito; S. Sreehari Sastry; Siew Teng Ong

    2011-01-01

    New Schiff base liquid crystals containing benzoxazole core and alkanoyloxy chain at the end group of the molecules (Cn-1H2n-1COO-, n= 14,16,18) was synthesized. The present compounds are enantiotropic smectic A liquid crystals. It was also found that the end groups of the molecules and polar chloro substituent at the benzoxazole fragment had effect on the mesomorphic properties.

  4. Slab photonic crystals with dimer colloid bases

    Energy Technology Data Exchange (ETDEWEB)

    Riley, Erin K.; Liddell Watson, Chekesha M., E-mail: cliddell@ccmr.cornell.edu [Department of Materials Science and Engineering, Cornell University, 128 Bard Hall Ithaca, New York 14853 (United States)

    2014-06-14

    The photonic band gap properties for centered rectangular monolayers of asymmetric dimers are reported. Colloids in suspension have been organized into the phase under confinement. The theoretical model is inspired by the range of asymmetric dimers synthesized via seeded emulsion polymerization and explores, in particular, the band structures as a function of degree of lobe symmetry and degree of lobe fusion. These parameters are varied incrementally from spheres to lobe-tangent dimers over morphologies yielding physically realizable particles. The work addresses the relative scarcity of theoretical studies on photonic crystal slabs with vertical variation that is consistent with colloidal self-assembly. Odd, even and polarization independent gaps in the guided modes are determined for direct slab structures. A wide range of lobe symmetry and degree of lobe fusion combinations having Brillouin zones with moderate to high isotropy support gaps between odd mode band indices 3-4 and even mode band indices 1-2 and 2-3.

  5. Optical detection of sepsis markers using liquid crystal based biosensors

    Science.gov (United States)

    McCamley, Maureen K.; Artenstein, Andrew W.; Opal, Steven M.; Crawford, Gregory P.

    2007-02-01

    A liquid crystal based biosensor for the detection and diagnosis of sepsis is currently in development. Sepsis, a major clinical syndrome with a significant public health burden in the US due to a large elderly population, is the systemic response of the body to a localized infection and is defined as the combination of pathologic infection and physiological changes. Bacterial infections are responsible for 90% of cases of sepsis in the US. Currently there is no bedside diagnostic available to positively identify sepsis. The basic detection scheme employed in a liquid crystal biosensor contains attributes that would find value in a clinical setting, especially for the early detection of sepsis. Utilizing the unique properties of liquid crystals, such as birefringence, a bedside diagnostic is in development which will optically report the presence of biomolecules. In a septic patient, an endotoxin known as lipopolysaccharide (LPS) is released from the outer membrane of Gram-negative bacteria and can be found in the blood stream. It is hypothesized that this long chained molecule will cause local disruptions to the open surface of a sensor containing aligned liquid crystal. The bulk liquid crystal ampli.es these local changes at the surface due to the presence of the sepsis marker, providing an optical readout through polarizing microscopy images. Liquid crystal sensors consisting of both square and circular grids, 100-200 μm in size, have been fabricated and filled with a common liquid crystal material, 5CB. Homeotropic alignment was confirmed using polarizing microscopy. The grids were then contacted with either saline only (control), or saline with varying concentrations of LPS. Changes in the con.guration of the nematic director of the liquid crystal were observed through the range of concentrations tested (5mg/mL - 1pg/mL) which have been confirmed by a consulting physician as clinically relevant levels.

  6. Optical modulator based on coupled photonic crystal cavities

    Science.gov (United States)

    Serafimovich, Pavel G.; Kazanskiy, Nikolay L.

    2016-07-01

    We propose and numerically investigate an optical signal modulator based on two-photonic crystal nanobeam cavities coupled through a waveguide. The suggested modulator shifts the resonant frequency over a scalable range. We design a compact optical modulator based on photonic crystal nanobeams cavities that exhibits high stability to manufacturing. Photonic crystal waveguide tuning in the low-intensity region of the resonant mode is demonstrated. The advantages of the suggested approach over the single-resonator optical modulator approaches include the possibilities to shift the modulator frequency over a scalable range that depends on switching energy level and to effectively electrically tune the device in the low-intensity region of the resonant mode.

  7. Photonic crystal waveguides based on an antiresonant reflecting platform

    DEFF Research Database (Denmark)

    Lavrinenko, Andrei; Frandsen, Lars Hagedorn; Fage-Pedersen, Jacob;

    2005-01-01

    We apply the antiresonant reflecting layers arrangement to silicon-on-insulator based photonic crystal waveguides. Several layered structures with different combinations of materials (Si-SiO2, Si3N4-SiO2) and layer topology have been analysed. Numerical modelling using 3D Finite-Difference Time...

  8. Coherent pair production in deformed crystals with a complex base

    CERN Document Server

    Mkrtchyan, A R; Saharian, A A

    2006-01-01

    We investigate the coherent electron-positron pair creation by high-energy photons in a periodically deformed single crystal with a complex base. The formula for the corresponding differential cross-section is derived for an arbitrary deformation field. The conditions are specified under which the influence of the deformation is considerable. The case is considered in detail when the photon enters into the crystal at small angles with respect to a crystallographic axis. The results of the numerical calculations are presented for $\\mathrm{SiO}_{2}$ single crystal and Moliere parametrization of the screened atomic potentials in the case of the deformation field generated by the acoustic wave of $S$ type. In dependence of the parameters, the presence of deformation can either enhance or reduce the pair creation cross-section. This can be used to control the parameters of the positron sources for storage rings and colliders.

  9. Optical parametric chirped pulse amplification based on photonic crystal fibre

    Institute of Scientific and Technical Information of China (English)

    Wang He-Lin; Yang Ai-Jun; Leng Yu-Xin; Wang Cheng; Xu Zhi-Zhan; Hou Lan-Tian

    2011-01-01

    A compact two-stage optical parametric chirped pulse amplifier based on photonic crystal fibre is demonstrated.A 1064-nm soliton pulse is obtained in a home-made photonic crystal fibre(PCF)with femtosecond pulse pumping and then amplified to 2 mJ in an Nd:YAG regenerative amplifier.After the amplified pulses pass through the LBO crystal,the 532-nm double-frequency light with an energy of 0.8 mJ and a duration of over 100 ps at 10-Hz repetition rate is generated as a pump source in the following two-stage optical parametric amplification(OPA).The 850-am chirped signal light gain from the stretcher is 1.5×104in the first-stage OPA while it is 120 in the second-stage OPA.The total signal gain of optical parametric chirped pulse amplification(OPCPA)can reach 1.8×106.

  10. A new membrane-based crystallization technique: tests on lysozyme

    Science.gov (United States)

    Curcio, Efrem; Profio, Gianluca Di; Drioli, Enrico

    2003-01-01

    The great importance of protein science both in industrial and scientific fields, in conjunction with the intrinsic difficulty to grow macromolecular crystals, stimulates the development of new observations and ideas that can be useful in initiating more systematic studies using novel approaches. In this regard, an innovative technique, based on the employment of microporous hydrophobic membranes in order to promote the formation of lysozyme crystals from supersaturated solutions, is introduced in this work. Operational principles and possible advantages, both in terms of controlled extraction of solvent by acting on the concentration of the stripping solution and reduced induction times, are outlined. Theoretical developments and experimental results concerning the mass transfer, in vapour phase, through the membrane are presented, as well as the results from X-ray diffraction to 1.7 Å resolution of obtained lysozyme crystals using NaCl as the crystallizing agent and sodium acetate as the buffer. Crystals were found to be tetragonal with unit cell dimensions of a= b=79.1 Å and c=37.9 Å; the overall Rmerge on intensities in the resolution range from 25 to 1.7 Å was, in the best case, 4.4%.

  11. Self Assembled Monolayers for Quartz Crystal Microbalance based Biosensing

    OpenAIRE

    Myrskog, Annica

    2009-01-01

    The work in this thesis has been focused on developing surfaces for use in biosensor systems, especially for quartz crystal microbalances. The surfaces were prepared by adsorption of organosulfur molecules onto gold substrates, so called self assembled monolayers (SAMs). By chemical synthesis these thiols can be specifically tailored to provide surfaces with desired properties. The investigated surfaces were all based on thiols terminated with carboxylic acid groups to render hydrophilic surf...

  12. Singly-resonant optical parametric oscillator based on KTA crystal

    Indian Academy of Sciences (India)

    S Das; S Gangopadhyay; C Ghosh; G C Bhar

    2005-01-01

    Tunable mid-infra-red radiation by singly resonant optical parametric oscillation based on KTA crystal pumped by multi-axial Gaussian shape beam from Q-switched Nd:YAG laser has been demonstrated. Threshold energy of oscillation at different idler wavelengths for different cavity length has been demonstrated. Single pass conversion efficiency of incident pump energy to infra-red wavelength has also been measured.

  13. Optical microcavities based on surface modes in two-dimensional photonic crystals and silicon-on-insulator photonic crystals

    DEFF Research Database (Denmark)

    Xiao, Sanshui; Qiu, M.

    2007-01-01

    Surface-mode optical microcavities based on two-dimensional photonic crystals and silicon-on-insulator photonic crystals are studied. We demonstrate that a high-quality-factor microcavity can be easily realized in these structures. With an increasing of the cavity length, the quality factor is gr...

  14. Magnesium and cadmium containing Heusler phases REPd2Mg, REPd2Cd, REAg2Mg, REAu2Mg and REAu2Cd

    Science.gov (United States)

    Johnscher, Michael; Stein, Sebastian; Niehaus, Oliver; Benndorf, Christopher; Heletta, Lukas; Kersting, Marcel; Höting, Christoph; Eckert, Hellmut; Pöttgen, Rainer

    2016-02-01

    Twenty-eight new Heusler phases REPd2Mg, REPd2Cd, REAg2Mg, REAu2Mg and REAu2Cd with different rare earth elements were synthesized from the elements in sealed niobium ampoules in a water-cooled sample chamber of an induction furnace. The samples were characterized by powder X-ray diffraction. The cell volumes show the expected lanthanide contraction. The structures of YPd2Cd, GdPd2Cd, GdAu2Cd, Y1.12Ag2Mg0.88 and GdAg2Mg were refined based on single crystal diffractometer data. The magnetic properties were determined for fifteen phase pure samples. LuAu2Mg is a weak Pauli paramagnet with a susceptibility of 1.0(2) × 10-5 emu mol-1 at room temperature. The remaining samples show stable trivalent rare earth ions and most of them order magnetically at low temperatures. The ferromagnet GdAg2Mg shows the highest ordering temperature of TC = 98.3 K. 113Cd and 89Y MAS NMR spectra of YAu2Cd and YPd2Cd confirm the presence of unique crystallographic sites. The resonances are characterized by large Knight shifts, whose magnitude can be correlated with electronegativity trends.

  15. Crystal chemistry and structural design of iron-based superconductors

    Institute of Scientific and Technical Information of China (English)

    Jiang Hao; Sun Yun-Lei; Xu Zhu-An; Cao Guang-Han

    2013-01-01

    The second class of high-temperature superconductors (HTSCs),iron-based pnictides and chalcogenides,necessarily contain Fe2X2 (“X” refers to a pnictogen or a chalcogen element) layers,just like the first class of HTSCs which possess the essential CuO2 sheets.So far,dozens of iron-based HTSCs,classified into nine groups,have been discovered.In this article,the crystal-chemistry aspects of the known iron-based superconductors are reviewed and summarized by employing “hard and soft acids and bases (HSAB)” concept.Based on these understandings,we propose an alternative route to exploring new iron-based superconductors via rational structural design.

  16. Photonic-crystal-based all-optical NOT logic gate.

    Science.gov (United States)

    Singh, Brahm Raj; Rawal, Swati

    2015-12-01

    In the present paper, we have utilized the concept of photonic crystals for the implementation of an optical NOT gate inverter. The designed structure has a hexagonal arrangement of silicon rods in air substrate. The logic function is based on the phenomenon of the existence of the photonic bandgap and resulting guided modes in defect photonic crystal waveguides. We have plotted the transmission, extinction ratio, and tolerance analysis graphs for the structure, and it has been observed that the maximum output is obtained for a telecom wavelength of 1.554 μm. Dispersion curves are obtained using the plane wave expansion method, and the transmission is simulated using the finite element method. The proposed structure is applicable for photonic integrated circuits due to its simple structure and clear operating principle. PMID:26831380

  17. CVD synthesis of carbon-based metallic photonic crystals

    CERN Document Server

    Zakhidov, A A; Baughman, R H; Iqbal, Z

    1999-01-01

    Three-dimensionally periodic nanostructures on the scale of hundreds of nanometers, known as photonic crystals, are attracting increasing interest because of a number of exciting predicted properties. In particular, interesting behavior should be obtainable for carbon- based structures having a dimensional scale larger than fullerenes and nanotubes, but smaller than graphitic microfibers. We show here how templating of porous opals by chemical vapor deposition (CVD) allows us to obtain novel types of graphitic nanostructures. We describe the synthesis of new cubic forms of carbon having extended covalent connectivity in three dimensions, which provide high electrical conductivity and unit cell dimensions comparable to optical wavelengths. Such materials are metallic photonic crystals that show intense Bragg diffraction. (14 refs).

  18. Proton irradiation of liquid crystal based adaptive optical devices

    International Nuclear Information System (INIS)

    To assess its radiation hardness, a liquid crystal based adaptive optical element has been irradiated using a 60 MeV proton beam. The device with the functionality of an optical beam steerer was characterised before, during and after the irradiation. A systematic set of measurements on the transmission and beam deflection angles was carried out. The measurements showed that the transmission decreased only marginally and that its optical performance degraded only after a very high proton fluence (1010p/cm2). The device showed complete annealing in the functionality as a beam steerer, which leads to the conclusion that the liquid crystal technology for optical devices is not vulnerable to proton irradiation as expected in space.

  19. Solution-based metal induced crystallization of a-Si

    Institute of Scientific and Technical Information of China (English)

    Wu Chun-Ya; Li Xue-Dong; Zhao Shu-Yun; Li Juan; Meng Zhi-Guo; Xiong Shao-Zhen; Zhang Fang

    2009-01-01

    This paper investigates a simplified metal induced crystallization (MIC) of a-Si, named solution-based MIC (S-MIC). The nickel inducing source was formed on a-Si from salt solution dissolved in de-ionized water or ethanol. a-Si thin film was deposited with low pressure chemical vapour deposition or plasma enhanced chemical vapour deposition as precursor material for MIC. It finds that the content of nickel source formed on a-Si can be controlled by solution concentration and dipping time. The dependence of crystallization rate of a-Si on annealing time illustrated that the linear density of nickel source was another critical factor that affects the crystallization of a-Si, besides the diffusion of nickel disilicide. The highest electron Hall mobility of thus prepared S-MIC poly-Si is 45.6cm2/(V路s). By using this S-MIC poly-Si, thin film transistors and display scan drivers were made, and their characteristics are presented.

  20. Thermally Driven Photonic Actuator Based on Silica Opal Photonic Crystal with Liquid Crystal Elastomer.

    Science.gov (United States)

    Xing, Huihui; Li, Jun; Shi, Yang; Guo, Jinbao; Wei, Jie

    2016-04-13

    We have developed a novel thermoresponsive photonic actuator based on three-dimensional SiO2 opal photonic crystals (PCs) together with liquid crystal elastomers (LCEs). In the process of fabrication of such a photonic actuator, the LCE precursor is infiltrated into the SiO2 opal PC followed by UV light-induced photopolymerization, thereby forming the SiO2 opal PC/LCE composite film with a bilayer structure. We find that this bilayer composite film simultaneously exhibits actuation behavior as well as the photonic band gap (PBG) response to external temperature variation. When the SiO2 opal PC/LCE composite film is heated, it exhibits a considerable bending deformation, and its PBG shifts to a shorter wavelength at the same time. In addition, this actuation is quite fast, reversible, and highly repeatable. The thermoresponsive behavior of the SiO2 opal PC/LCE composite films mainly derives from the thermal-driven change of nematic order of the LCE layer which leads to the asymmetric shrinkage/expansion of the bilayer structure. These results will be of interest in designing optical actuator systems for environment-temperature detection.

  1. Searching for the Best Protein Crystals: Synchrotron Based Measurements of Protein Crystal Quality

    Science.gov (United States)

    Borgstahl, Gloria; Snell, Edward H.; Bellamy, Henry; Pangborn, Walter; Nelson, Chris; Arvai, Andy; Ohren, Jeff; Pokross, Matt

    1999-01-01

    We are developing X-ray diffraction methods to quantitatively evaluate the quality of protein crystals. The ultimate use for these crystal quality will be to optimize crystal growth and freezing conditions to obtain the best diffraction data. We have combined super fine-phi slicing with highly monochromatic, low divergence synchrotron radiation and the ADSC Quantum 4 CCD detector at the Stanford Synchrotron Radiation laboratory beamline 1.5 to accurately measure crystal mosaicity. Comparisons of microgravity versus earth-grown insulin crystals using these methods will be presented.

  2. Laser Coherence Meter Based on Nanostructured Liquid Crystals

    Directory of Open Access Journals (Sweden)

    A. Anczykowska

    2013-01-01

    Full Text Available We present the method for coherence length measurement using coherence meter based on hybrid liquid crystal structures doped with gold nanoparticles. The results indicate that the method is able to determine the coherence length of coherent light sources with precision of 0.01 m at wavelength range from 200 to 800 nm for wide range of initial beam powers starting from 1 mW. Given the increasing use of laser technology in industry, military, or medicine, our research may open up a possible route for the development of improved techniques of coherent diagnostic light sources.

  3. Polarization converters based on axially symmetric twisted nematic liquid crystal.

    Science.gov (United States)

    Ko, Shih-Wei; Ting, Chi-Lun; Fuh, Andy Y-G; Lin, Tsung-Hsien

    2010-02-15

    An axially symmetric twisted nematic liquid crystal (ASTNLC) device, based on axially symmetric photoalignment, was demonstrated. Such an ASTNLC device can convert axial (azimuthal) to azimuthal (axial) polarization. The optical properties of the ASTNLC device are analyzed and found to agree with simulation results. The ASTNLC device with a specific device can be adopted as an arbitrary axial symmetric polarization converter or waveplate for axially, azimuthally or vertically polarized light. A design for converting linear polarized light to axially symmetric circular polarized light is also demonstrated. PMID:20389369

  4. Photonic Crystal Biosensor Based on Optical Surface Waves

    Directory of Open Access Journals (Sweden)

    Giovanni Dietler

    2013-02-01

    Full Text Available A label-free biosensor device based on registration of photonic crystal surface waves is described. Angular interrogation of the optical surface wave resonance is used to detect changes in the thickness of an adsorbed layer, while an additional simultaneous detection of the critical angle of total internal reflection provides independent data of the liquid refractive index. The abilities of the device are demonstrated by measuring of biotin molecule binding to a streptavidin monolayer, and by measuring association and dissociation kinetics of immunoglobulin G proteins. Additionally, deposition of PSS / PAH polyelectrolytes is recorded in situ resulting calculation of PSS and PAH monolayer thicknesses separately.

  5. A Nanofluidic Biosensor Based on Nanoreplica Molding Photonic Crystal

    Science.gov (United States)

    Peng, Wang; Chen, Youping; Ai, Wu; Zhang, Dailin

    2016-09-01

    A nanofluidic biosensor based on nanoreplica molding photonic crystal (PC) was proposed. UV epoxy PC was fabricated by nanoreplica molding on a master PC wafer. The nanochannels were sealed between the gratings on the PC surface and a taped layer. The resonance wavelength of PC-based nanofluidic biosensor was used for testing the sealing effect. According to the peak wavelength value of the sensor, an initial label-free experiment was realized with R6g as the analyte. When the PC-based biosensor was illuminated by a monochromatic light source with a specific angle, the resonance wavelength of the sensor will match with the light source and amplified the electromagnetic field. The amplified electromagnetic field was used to enhance the fluorescence excitation result. The enhancement effect was used for enhancing fluorescence excitation and emission when matched with the resonance condition. Alexa Fluor 635 was used as the target dye excited by 637-nm laser source on a configured photonic crystal enhanced fluorescence (PCEF) setup, and an initial PCEF enhancement factor was obtained.

  6. Crystallization of Mg-based bulk metallic glass

    Institute of Scientific and Technical Information of China (English)

    CHEN Gang; M. FERRY

    2006-01-01

    Mg-based bulk metallic glass fabricated by conventional copper mould method was aged at different temperatures. X-ray diffractometry(XRD), scanning electron microscopy(SEM), atomic force microscopy(AFM) and focused ion beam(FIB) miller were employed to examine specimens obtained under different conditions. The crystallization of Mg-based bulk metallic glass depends upon both the aging temperature and the aging time. As temperature increases or the holding time increases, the microstructure of the aged specimen varies from glassy one to crystalline one plus glassy phase and then to absolutely multiphase crystalline one. From the FIB images, it is clear that Mg-based bulk metallic glass could not only crystallize completely but also display dendrite-like growth style. From the AFM images, there are not only significant variations of microstructures but also surface morphology of specimens obtained under different conditions. It is proposed that the surface morphology varies as the treating temperature increases. The Vickers hardness of different specimens increases as the fraction of crystalline phase (s) increases.

  7. AFM research on Fe-based nanocrystal crystallization mechanism

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The cross-section pattern of Fe-based alloy ribbon (Fe73.5Cu1Nb3Si13.5B9) annealed at different temperatures was investigated by AFM (atomic force microscope), and the effect mechanism of Nb and Cu in Fe-based alloy ribbon annealing was analyzed with XRD diffraction crystal analysis technique and other research results. New concepts of encapsulated grain, Nb vacancy cluster, Nb-B atom cluster and so on were proposed and used to describe the formation mechanism of α-Fe (Si) nanocrystal. Finally, a three-phase (separation phase, encapsulated phase and nanocrystalline phase) interconnected structure model in Fe-based nanocrystalline alloy was established.

  8. Prospects of quantum-dots-based liquid-crystal displays

    Science.gov (United States)

    Luo, Zhenyue; Xu, Su; Chen, Yuan; Liu, Yifan; Wu, Shin-Tson

    2014-02-01

    We report a systematic photometric study of LCD based on quantum dot (QD) backlight, and find the optimal emission spectrum combination in terms of system efficiency and wide color gamut. A QD-based LCD has potential to achieve 120% AdobeRGB color gamut in CIE 1931 and 140% in CIE 1976 color space, while keeping the same energy efficiency as conventional backlights. Moreover, we present a transmissive color display based on voltage-stretchable liquid crystal droplet and quantum dot backlight. This polarizer-free display exhibits highly saturated colors, wide viewing angle and reasonably good contrast ratio. QD backlight allows LCD to display original colors with high fidelity, which makes LCD more competitive to organic LED. The prime time for QD-enhanced LCDs is near.

  9. Digital photofinishing system based on liquid crystal on silicon

    Science.gov (United States)

    Zheng, Minmin; Yan, Huimin; Zhang, Xiuda; Du, Yanli

    2006-01-01

    As the digital camera user base grows, so does the demand for digital imaging services. A new digital photo finishing system based on Liquid Crystal On Silicon (LCOS) is presented. The LCOS panel motherboard is made up of CMOS chip. Three individual streams of light (red, green, blue) are directed to corresponding Polarization Beam Spliter (PBS) to make the S polarization beam arrive at LCOS panel. When the Liquid appears light, the S polarization beam is changed to P polarization beam and reflected to pass through Polarization Beam Spliter. Compared with Thin Film Transistor-Liquid Crystal Display (TFT-LCD), LCOS has many merits including high resolution, high contrast, wide viewing angle, low cost and so on. In this work, we focus on the way in which the images will be displayed on LCOS. A liquid crystal on silicon microdisplay driver circuit for digital photo finishing system has been designed and fabricated using BRILLIAN microdisplay driver lite(MDD-LITE) ASIC and LCOS SXGA (1280×1024 pixel) with a 0.78"(20mm) diagonal active matrix reflective mode LCD. The driver includes a control circuit, which presents serial data, serial clock , write protect signals and control signals for LED, and a mixed circuit which implements RGB signal to input the LCOS. According to a minimum error sum of squares algorithm, we find a minimum offset and then shift RGB optical intensity vs voltage curves right and left to make these three curves almost coincide with each other. The design had great application in the digital photo finishing.

  10. Emerging Applications of Liquid Crystals Based on Nanotechnology

    Directory of Open Access Journals (Sweden)

    Jung Inn Sohn

    2014-03-01

    Full Text Available Diverse functionalities of liquid crystals (LCs offer enormous opportunities for their potential use in advanced mobile and smart displays, as well as novel non-display applications. Here, we present snapshots of the research carried out on emerging applications of LCs ranging from electronics to holography and self-powered systems. In addition, we will show our recent results focused on the development of new LC applications, such as programmable transistors, a transparent and active-type two-dimensional optical array and self-powered display systems based on LCs, and will briefly discuss their novel concepts and basic operating principles. Our research will give insights not only into comprehensively understanding technical and scientific applications of LCs, but also developing new discoveries of other LC-based devices.

  11. Photonic crystal-based RGB primary colour optical filter

    Science.gov (United States)

    Singh, Brahm Raj; Rawal, Swati; Sinha, R. K.

    2016-08-01

    We have presented an RGB optical filter, based on photonic crystal (PhC) waveguides, with the hexagonal arrangement of GaP rods in air. It filters out the three primary colours of the visible range, red (R, λ = 648 nm), green (G, λ = 540 nm) and blue (B, λ = 470 nm). The plane wave expansion method is applied for estimating the dispersion curves and finite element method is utilized in examining the propagation characteristics of the designed PhC-based optical filter. Transmittance, extinction ratio and tolerance analysis have further been calculated to confirm the performance of the proposed optical filter to work in the visible range of optical spectrum and filter out the three primary colours (red, green, blue) along different output ports.

  12. Growth and Characterization on PMN-PT-Based Single Crystals

    Directory of Open Access Journals (Sweden)

    Jian Tian

    2014-07-01

    Full Text Available Lead magnesium niobate—lead titanate (PMN-PT single crystals have been successfully commercialized in medical ultrasound imaging. The superior properties of PMN-PT crystals over the legacy piezoelectric ceramics lead zirconate titanate (PZT enabled ultrasound transducers with enhanced imaging (broad bandwidth and improved sensitivity. To obtain high quality and relatively low cost single crystals for commercial production, PMN-PT single crystals were grown with modified Bridgman method, by which crystals were grown directly from stoichiometric melt without flux. For ultrasound imaging application, [001] crystal growth is essential to provide uniform composition and property within a crystal plate, which is critical for transducer performance. In addition, improvement in crystal growth technique is under development with the goals of improving the composition homogeneity along crystal growth direction and reducing unit cost of crystals. In recent years, PIN-PMN-PT single crystals have been developed with higher de-poling temperature and coercive field to provide improved thermal and electrical stability for transducer application.

  13. Photonic Crystal Fibre SERS Sensors Based on Silver Nanoparticle Colloid

    Institute of Scientific and Technical Information of China (English)

    XIE Zhi-Guo; LU Yong-Hua; WANG Pei; LIN Kai-Qun; YAN Jie; MING Hai

    2008-01-01

    @@ A photonic crystal fibre (PCF) surface enhanced Raman scattering (SERS) sensor is developed based on silver nanoparticle colloid.Analyte solution and silver nanoparticles are injected into the air holes of PCF by a simple modified syringe to overcome maes-transport constraints, allowing more silver nanoparticles involved in SERS activity.This sensor offers significant benefit over the conventional SERS sensor with high flexibility, easy manufacture.We demonstrate the detection of 4-mercaptobenzoic acid (4-MBA ) molecules with the injecting way and the common dipping measurement.The injecting way shows obviously better results than the dipping one.Theoretical analysis indicates that this PCF SERS substrate offers enhancement of about 7 orders of magnitude in SERS active area.

  14. Magnetic field measurements based on Terfenol coated photonic crystal fibers.

    Science.gov (United States)

    Quintero, Sully M M; Martelli, Cicero; Braga, Arthur M B; Valente, Luiz C G; Kato, Carla C

    2011-01-01

    A magnetic field sensor based on the integration of a high birefringence photonic crystal fiber and a composite material made of Terfenol particles and an epoxy resin is proposed. An in-fiber modal interferometer is assembled by evenly exciting both eigenemodes of the HiBi fiber. Changes in the cavity length as well as the effective refractive index are induced by exposing the sensor head to magnetic fields. The magnetic field sensor has a sensitivity of 0.006 (nm/mT) over a range from 0 to 300 mT with a resolution about ±1 mT. A fiber Bragg grating magnetic field sensor is also fabricated and employed to characterize the response of Terfenol composite to the magnetic field.

  15. Terahertz wave filter based on cinquefoil photonic crystal

    Science.gov (United States)

    Sun, Chao; Li, Jiu-sheng

    2012-03-01

    There are increasing demands for experiments in terahertz frequencies, in different areas such as biotechnology, nanotechnology, space science, security, terahertz wave communications, and plasma diagnostics. For potential applications, the functional devices, such as beam polarizers, modulators and filters, are crucuial components for a terahertz system. As a dispensable device for ultrafast information processing and interconnection of terahertz wave communication, terahertz wave filter has attracted considerable attention. In this paper, we design the terahertz wave filter structure based on three kinds of photonic crystals structures. The finite-difference time-domain (FDTD) has been employed to analysis the performances of these terahertz wave filters. The simulation results show that these designed filters exhibit excellent transmission performance such as high transmission at the central frequency, adjustable bandpass, and good rejection of the sideband frequencies. Three kinds of compact and integrated terahertz wave filters are obtained.

  16. Single Crystal DMs for Space-Based Observatories

    Science.gov (United States)

    Bierden, Paul

    We propose to demonstrate the feasibility of a new manufacturing process for large aperture, high-actuator count microelectromechanical deformable mirrors (MEMS-DMs). These DMs are designed to fill a critical technology gap in NASA s plan for high- contrast space-based exoplanet observatories. We will manufacture a prototype DM with a continuous mirror facesheet, having an active aperture of 50mm diameter, supported by 2040 electrostatic actuators (50 across the diameter of the active aperture), spaced at a pitch of 1mm. The DM will be manufactured using silicon microfabrication tools. The strategic motivation for the proposed project is to advance MEMS DMs as an enabling technology in NASA s rapidly emerging program for extrasolar planet exploration. That goal is supported by an Astro2010 white paper on Technologies for Direct Optical Imaging of Exoplanets, which concluded that DMs are a critical component for all proposed internal coronagraph instrument concepts. That white paper pointed to great strides made by DM developers in the past decade, and acknowledged the components made by Boston Micromachines Corporation to be the most notable MEMS-based technology option. The principal manufacturing innovation in this project will be assembly of the DM through fusion bonding of three separate single crystal silicon wafers comprising the device s substrate, actuator array, and facesheet. The most significant challenge of this project will be to develop processes that allow reliable fusion bonds between multiple compliant silicon layers while yielding an optically flat surface and a robust electromechanical system. The compliance of the DM, which is required for its electromechanical function, will make it challenging to achieve the intimate, planar contact that is generally needed for success in fusion bonding. The manufacturing approach will use photolithography and reactive ion etching to pattern structural layers. Three wafer-scale devices will be patterned and

  17. Pressure sensor based on flexible photonic crystal membrane.

    Science.gov (United States)

    Karrock, Torben; Gerken, Martina

    2015-12-01

    We demonstrate a pressure sensor based on deformation of a periodically nanostructured Bragg grating waveguide on a flexible 50 µm polydimethylsiloxane membrane and remote optical read out. A pressure change causes deformation of this 2 mm diameter photonic crystal membrane sealing a reference volume. The resulting shift of the guided mode resonances is observed by a remote camera as localized color change. Crossed polarization filters are employed for enhancing the visibility of the guided mode resonances. Pressure values are calculated from the intensity change in the green color channel using a calibration curve in the range of 2000 Pa to 4000 Pa. A limit of detection (LOD) of 160 Pa is estimated. This LOD combined with the small size of the sensor and its biocompatibility render it promising for application as an implantable intraocular pressure sensor.

  18. Cholesteric Liquid Crystal Based Reflex Color Reflective Displays

    Science.gov (United States)

    Khan, Asad

    2012-02-01

    Bistable color cholesteric liquid crystal displays are unique LCDs that exhibit high reflectivity, good contrast, extremely low power operation, and are amenable to versatile roll-to-roll manufacturing. The display technology, now branded as Reflex has been in commercialized products since 1996. It has been the subject of extensive research and development globally by a variety of parties in both academic and industrial settings. Today, the display technology is in volume production for applications such as dedicated eWriters (Boogie Board), full color electronic skins (eSkin), and displays for smart cards. The flexibility comes from polymerization induced phase separation using unique materials unparalleled in any other display technology. The blend of monomers, polymers, cross linkers, and other components along with nematic liquid crystals and chiral dopants is created and processed in such ways so as to enable highly efficient manufactrable displays using ultra thin plastic substrates -- often as thin as 50μm. Other significant aspects include full color by stacking or spatial separation, night vision capability, ultra high resolution, as well as active matrix capabilities. Of particular note is the stacking approach of Reflex based displays to show full color. This approach for reflective color displays is unique to this technology. Owing to high transparency in wavelength bands outside the selective reflection band, three primarily color layers can be stacked on top of each other and reflect without interfering with other layers. This highly surprising architecture enables the highest reflectivity of any other reflective electronic color display technology. The optics, architecture, electro-topics, and process techniques will be discussed. This presentation will focus on the physics of the core technology and color, it's evolution from rigid glass based displays to flexible displays, development of products from the paradigm shifting concepts to consumer

  19. Crystal growth iron based pnictide compounds; Kristallzuechtung eisenbasierter Pniktidverbindungen

    Energy Technology Data Exchange (ETDEWEB)

    Nacke, Claudia

    2012-11-15

    The present work is concerned with selected crystal growth method for producing iron-based superconductors. The first part of this work introduces significant results of the crystal growth of BaFe{sub 2}As{sub 2} and the cobalt-substituted compound Ba(Fe{sub 1-x}Co{sub x}){sub 2}As{sub 2} with x{sub Nom} = 0.025, 0.05, 0.07, 0.10 and 0.20. For this purpose a test procedure for the vertical Bridgman method was developed. The second part of this work contains substantial results for growing a crystal of LiFeAs and the nickel-substituted compound Li{sub 1-δ}Fe{sub 1-x}Ni{sub x}As with x{sub Nom} = 0.015, 0.025, 0.05, 0.06, 0.075 and 0.10. For this purpose a test procedure for the melt flow process has been developed successfully. [German] Die vorliegende Arbeit befasst sich mit ausgewaehlten Kristallzuechtungsverfahren zur Herstellung eisenbasierter Supraleiter. Der erste Teil dieser Arbeit fuehrt wesentliche Ergebnisse der Kristallzuechtung von BaFe{sub 2}As{sub 2} sowie der Cobalt-substituierten Verbindung Ba(Fe{sub 1-x}Co{sub x}){sub 2}As{sub 2} mit x{sub Nom} =0.025, 0.05, 0.07, 0.10 und 0.20 auf. Hierzu wurde eine Versuchsdurchfuehrung fuer das vertikale Bridgman-Verfahren konzipiert, mit welcher erfolgreich Kristalle dieser Zusammensetzungen gezuechtet wurden. Der zweite Teil dieser Arbeit enthaelt wesentliche Ergebnisse zur Kristallzuechtung von LiFeAs sowie der Nickel-substituierten Verbindung Li{sub 1-δ}Fe{sub 1-x}Ni{sub x}As mit x{sub Nom} = 0.015, 0.025, 0.05, 0.06, 0.075 und 0.10. Hierfuer wurde erfolgreich eine Versuchsdurchfuehrung fuer das Schmelzfluss-Verfahren entwickelt.

  20. Optimization of salt concentration in PEG-based crystallization solutions

    OpenAIRE

    Yamanaka, Mari; Inaka, Koji; Furubayashi, Naoki; Matsushima, Masaaki; Takahashi, Sachiko; Tanaka, Hiroaki; Sano, Satoshi; Sato, Masaru; Kobayashi, Tomoyuki; Tanaka, Tetsuo

    2010-01-01

    Although polyethylene glycol (PEG) is the most widely used precipitant in protein crystallization, the concentration of co-existing salt in the solution has not been well discussed. To determine the optimum salt concentration range, several kinds of protein were crystallized in a 30% PEG 4000 solution at various NaCl concentrations with various pH levels. It was found that, if crystallization occurred, the lowest effective salt concentration depended on the pH of the protein solution and the ...

  1. Degradation in single crystal nickel-base superalloys. A review

    Energy Technology Data Exchange (ETDEWEB)

    Nazmy, M.; Staubli, M. [Alstom (Switzerland) Ltd., Baden (Switzerland); Epishin, A. [Federal Institute for Material Research and Testing (BAM), Berlin (Germany); Link, T. [Technical Univ. Berlin (Germany)

    2006-07-01

    Single crystal Nickel-base superalloys are in use for the front rows of blading in advanced land-based gas turbines. This is for their higher creep capabilities as well as outstanding low cycle fatigue properties as compared with conventionally cast Nickel-base superalloys. The continuous efforts to improve the high temperature creep properties of SX superalloys resulted in the development of the fourth generation of these alloys. Nevertheless, this improvement in the high temperature capability of these materials required the use of higher contents of Re and Ru which increased their densities and costs. The application of SX superalloys at higher temperatures results in microstructural changes called rafting and a topological inversion of their {gamma}/{gamma}{sup '} phases. These two microstructural features reduce the tensile and low cycle fatigue properties of the SX superalloys. The extent of degradation in the microstructure and mechanical properties, in a certain SX superalloy, depends on the exposure temperature, duration and to a lesser extent on the applied stress. The consequences of these changes in microstructure and properties should be taken into consideration in the evaluation of the mechanical properties of SX superalloys. (orig.)

  2. Detection and recognition of analytes based on their crystallization patterns

    Science.gov (United States)

    Morozov, Victor; Bailey, Charles L.; Vsevolodov, Nikolai N.; Elliott, Adam

    2008-05-06

    The invention contemplates a method for recognition of proteins and other biological molecules by imaging morphology, size and distribution of crystalline and amorphous dry residues in droplets (further referred to as "crystallization pattern") containing predetermined amount of certain crystal-forming organic compounds (reporters) to which protein to be analyzed is added. It has been shown that changes in the crystallization patterns of a number of amino-acids can be used as a "signature" of a protein added. It was also found that both the character of changer in the crystallization patter and the fact of such changes can be used as recognition elements in analysis of protein molecules.

  3. New scintillating media based on liquid crystals for particle detectors

    CERN Document Server

    Barnik, M I; Vasilchenko, V G; Golovkin, S V; Medvedkov, A M; Soloviev, A S

    2000-01-01

    The study results of optical, photoluminiscent and scintillation properties of a liquid crystal 4-pentyl-4'-cyanobiphenyl are presented. The scintillation light output of this liquid crystal is about 35% of crystal anthracene, its main decay time constants are 4 and 14 ns, and the maximum of light emission spectrum is about 400 nm. The light output of a dissolution of green emitting light scintillation dopant R6 in the liquid crystal is about 120% of crystal anthracene. The light output of the frozen dissolution measured at -112 deg. C is about 2.5 times higher as observed at +20 deg. C. In the uniaxially oriented liquid crystal, the predominant intensity direction of emitted light is pointed perpendicular to the liquid crystal director and an appreciable part of the emitted light is elliptically polarized. The possibility to use scintillation properties of liquid crystals is considered both for the improvement of existing particle detector characteristics and for the creation of new gated particle detectors.

  4. Design and Fabrication of SOI-based photonic crystal components

    DEFF Research Database (Denmark)

    Borel, Peter Ingo; Frandsen, Lars Hagedorn; Harpøth, Anders;

    2004-01-01

    We present examples of ultra-compact photonic crystal components realized in silicon-on-insulator material. We have fabricated several different types of photonic crystal waveguide components displaying high transmission features. This includes 60° and 120° bends, different types of couplers, and...

  5. [Recent advancement of photonic-crystal-based analytical chemistry].

    Science.gov (United States)

    Chen, Yun; Guo, Zhenpeng; Wang, Jinyi; Chen, Yi

    2014-04-01

    Photonic crystals are a type of novel materials with ordered structure, nanopores/channels and optical band gap. They have hence important applications in physics, chemistry, biological science and engineering fields. This review summarizes the recent advancement of photonic crystals in analytical chemistry applications, with focus on sensing and separating fields happening in the nearest 5 years.

  6. Photonic crystal fiber based chloride chemical sensors for corrosion monitoring

    Science.gov (United States)

    Wei, Heming; Tao, Chuanyi; Krishnaswamy, Sridhar

    2016-04-01

    Corrosion of steel is one of the most important durability issues in reinforced concrete (RC) structures because aggressive ions such as chloride ions permeate concrete and corrode steel, consequently accelerating the destruction of structures, especially in marine environments. There are many practical methods for corrosion monitoring in RC structures, mostly focusing on electrochemical-based sensors for monitoring the chloride ion which is thought as one of the most important factors resulting in steel corrosion. In this work, we report a fiber-optic chloride chemical sensor based on long period gratings inscribed in a photonic crystal fiber (PCF) with a chloride sensitive thin film. Numerical simulation is performed to determine the characteristics and resonance spectral response versus the refractive indices of the analyte solution flowing through into the holes in the PCF. The effective refractive index of the cladding mode of the LPGs changes with variations of the analyte solution concentration, resulting in a shift of the resonance wavelength, hence providing the sensor signal. This fiber-optic chemical sensor has a fast response, is easy to prepare and is not susceptible to electromagnetic environment, and can therefore be of use for structural health monitoring of RC structures subjected to such aggressive environments.

  7. Crystal assembly based on 3,5-bis(2'-benzimidazole) pyridine and its complexes

    Science.gov (United States)

    Tong, Shan Ling; Tian, Zhao Yong; Wu, Ya Hong; Yan, Yan; Hu, Sheng; Yu, Jian

    2013-03-01

    Imdazole, pyridine and their derivatives have been considered as excellent ligands in supramolecular self-assembly. In this paper, a ligand molecule 3,5-bis (2'-benzimidazole) pyridine (BBP) was prepared, and two different crystal architectures based on the ligand molecule were self-assembled by diffusion/solvothermal ways. Furthermore, several crystal architectures of several relative complexes were also successfully assembled. These crystal structures were well defined by X-ray diffractions. Structural resolutions indicated that, as building blocks, this bibenzimidazole pyridine molecules exhibited coordination varieties in constructing the crystal architectures based on its related complexes.

  8. A HPMT based set-up to characterize scintillating crystals

    CERN Document Server

    D'Ambrosio, C; Jääskeläinen, S; Lecoeur, Gérard; Leutz, H; Loos, R; Piedigrossi, D; Puertolas, D; Rosso, E; Schomaker, R

    1999-01-01

    We have developed a fully automatic measurement set-up, capable of measuring light yields arising from scintillating crystals in a linear range of about four orders of magnitude. The photodetector is a Hybrid Photomultiplier Tube especially developed to optimize linear range and photon detection. Crystal and photodetector are temperature controlled by a closed water circuit, as this is essential when measuring low light yield scintillating crystals with a marked temperature dependence of their light yield. Gamma sources can be placed either on top or on the side of the crystal. In this latter case, the source can be automatically moved by a computer-controlled step motor to provide a uniformity profile of the light yield along the crystal. Tagged and not-tagged operation modes are possible. The whole set-up is computer-controlled in an effort to provide fast and reliable measurements, to characterize many crystals per day. This is important for the quality control of the Lead Tungstate crystals that will be a...

  9. Latest methods of fluorescence-based protein crystal identification

    International Nuclear Information System (INIS)

    Fluorescence, whether intrinsic or by using trace fluorescent labeling, can be a powerful aid in macromolecule crystallization. Its use in screening for crystals is discussed here. Successful protein crystallization screening experiments are dependent upon the experimenter being able to identify positive outcomes. The introduction of fluorescence techniques has brought a powerful and versatile tool to the aid of the crystal grower. Trace fluorescent labeling, in which a fluorescent probe is covalently bound to a subpopulation (<0.5%) of the protein, enables the use of visible fluorescence. Alternatively, one can avoid covalent modification and use UV fluorescence, exploiting the intrinsic fluorescent amino acids present in most proteins. By the use of these techniques, crystals that had previously been obscured in the crystallization drop can readily be identified and distinguished from amorphous precipitate or salt crystals. Additionally, lead conditions that may not have been obvious as such under white-light illumination can be identified. In all cases review of the screening plate is considerably accelerated, as the eye can quickly note objects of increased intensity

  10. Liquid crystal photoalignment material based on chloromethylated polyimide

    International Nuclear Information System (INIS)

    We report a liquid crystal photoalignment material with high photosensitivity and excellent thermal stability. The chloromethylated aromatic polyimide exhibited defect-free homogeneous alignment of liquid crystals upon irradiation of polarized deep ultraviolet (UV) for 50 s. The aligning ability of the film was retained up to 210 deg. C, and the cell containing liquid crystals could be stored at 85 deg. C for more than 14 days without any deterioration. FT-IR and UV-vis spectra confirmed that the alignment was induced by photodecomposition of polyimide, drastically accelerated by the introduction of chloromethyl side group

  11. Self-collimation-based photonic crystal Mach–Zehnder demultiplexer

    Science.gov (United States)

    Lee, Sun-Goo; Jung, Soo-Yong; Lee, Jongjin; Park, Jong-Moon; Kee, Chul-Sik

    2016-09-01

    A photonic crystal Mach–Zehnder demultiplexer (PC-MZDmux) with four output ports based on the self-collimation phenomenon in a two-dimensional (2D) PC is proposed and numerically studied using finite-difference time-domain simulations. The PC-MZDmux is composed of three Mach–Zehnder interferometers (MZIs) and each MZI consists of two 50:50 beam splitters and two perfect mirrors. Employed as the design parameters to achieve the demultiplexing functionality are the radius of phase control rods (PCRs) in the mirrors and the distance between the beam spitter and the mirror in the three MZIs. From spatial electric field distributions and transmission spectra, it is demonstrated that an incident self-collimated beam with four different frequencies can be demultiplexed to four output ports of the PC-MZDmux with proper design parameters. Our results indicate that this device design may constitute an efficient approach to light propagation manipulation and increase the application range of self-collimated beams.

  12. Liquid crystal based biosensors for bile acid detection

    Science.gov (United States)

    He, Sihui; Liang, Wenlang; Tanner, Colleen; Fang, Jiyu; Wu, Shin-Tson

    2013-03-01

    The concentration level of bile acids is a useful indicator for early diagnosis of liver diseases. The prevalent measurement method in detecting bile acids is the chromatography coupled with mass spectrometry, which is precise yet expensive. Here we present a biosensor platform based on liquid crystal (LC) films for the detection of cholic acid (CA). This platform has the advantage of low cost, label-free, solution phase detection and simple analysis. In this platform, LC film of 4-Cyano-4'-pentylbiphenyl (5CB) was hosted by a copper grid supported with a polyimide-coated glass substrate. By immersing into sodium dodecyl sulfate (SDS) solution, the LC film was coated with SDS which induced a homeotropic anchoring of 5CB. Addition of CA introduced competitive adsorption between CA and SDS at the interface, triggering a transition from homeotropic to homogeneous anchoring. The detection limit can be tuned by changing the pH value of the solution from 12uM to 170uM.

  13. A liquid-crystal-based DNA biosensor for pathogen detection

    Science.gov (United States)

    Khan, Mashooq; Khan, Abdur Rahim; Shin, Jae-Ho; Park, Soo-Young

    2016-03-01

    A liquid-crystal (LC)-filled transmission electron microscopy (TEM) grid cell coated with the cationic surfactant dodecyltrimethylammonium bromide (DTAB), to which a single-stranded deoxyribonucleic acid probe (ssDNAprobe) was adsorbed at the LC/aqueous interface (TEMDTAB/DNA), was applied for the highly specific detection of target DNA molecules. The DTAB-coated E7 (used LC mixture) in the TEM grid (TEMDTAB) exhibited a homeotropic orientation, and changed to a planar orientation upon adsorption of the ssDNAprobe. The TEMDTAB/DNA was then exposed to complementary (target) ssDNA, which resulted in a planar-to-homeotropic configurational change of E7 that could be observed through a polarized optical microscope under crossed polarizers. The optimum adsorption density (2 μM) of ssDNAprobe enabled the detection of ≥0.05 nM complementary ssDNA. This TEMDTAB/DNA biosensor could differentiate complementary ssDNA from mismatched ssDNA as well as double-stranded DNA. It also successfully detected the genomic DNAs of the bacterium Erwinia carotovora and the fungi Rhazictonia solani. Owe to the high specificity, sensitivity, and label-free detection, this biosensor may broaden the applications of LC-based biosensors to pathogen detection.

  14. Optical properties in the soft photonic crystals based on ferrofluids

    Energy Technology Data Exchange (ETDEWEB)

    Fan, C Z; Liang, E J [School of Physical Science and Engineering, and Key Laboratory of Materials Physics of Ministry of Education of China, Zhengzhou University, Zhengzhou 450052 (China); Huang, J P, E-mail: chunzhen@zzu.edu.cn [Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Fudan University, Shanghai 200433 (China)

    2011-08-17

    We theoretically investigate the properties of optical propagation in one-dimensional soft photonic crystals based on ferrofluids using the transfer matrix method. The proposed structure is composed of an alternating ferrofluid layer and a dielectric layer. Ferrofluids are composed of suspended ferromagnetic nanoparticles coated with silver, which has a frequency-dependent dielectric function. Core-shell nanocomposites incorporating an optical signature with magnetic response are particularly useful. The calculated results of dispersion relation show that tunable band gaps can be realized by varying the local magnetic field factor {alpha}, the shell thickness parameter t, or the filling fraction {nu} of the ferrofluid layer. An additional band gap appears in the lower frequency region due to the absorption. These band gaps blue shift when the external magnetic field is enhanced, and red shift when either t or {nu} is increased. We also extend our analysis to the variation of band width. To meet the requirements of optical devices, such a tunable structure can be used to design optical filters, modulators and waveguides.

  15. Kinetics of Non-Isothermal Crystallization of Coconut-based Cholesteryl Ester: Avrami and Ozawa Approache

    OpenAIRE

    J. F. Joson; L. T. Davila; Z. B. Domingo

    2003-01-01

    Kinetics of non-isothermal crystallization of coconut-based cholesteryl ester was performed by differentialscanning calorimetry under various heating rates. Different analysis methods were used to describe theprocess of non-isothermal crystallization. The results showed that the Avrami equation could describe thesystem very well. However, the Ozawa analysis failed. A probable reason is the difference in the crystallizationkinetics at high and low relative crystallization. The phase transition...

  16. A Novel Microwave Tunable Band-Pass Filter Integrated Power Divider Based on Liquid Crystal

    OpenAIRE

    Yupeng Liu; Di Jiang; Lei Xia; Ruimin Xu

    2015-01-01

    This paper proposes a novel microwave continuous adjustable band-pass filter integrated power divider based on nematic liquid crystals (LCs). The proposed power divider uses liquid crystal (LC) as the dielectric material. It can realize phase shift by changing the dielectric anisotropy, when biasing the high anisotropy nematic liquid crystal. It is mainly used in microwave frequencies. It has a large number of advantages compared to conventional filter integrated power divider, such as low lo...

  17. The Reflective Type of Electronic Whiteboard Based on Cholesteric Liquid Crystal Display Technology

    OpenAIRE

    TianHua Li

    2013-01-01

    The study analyzes the basic principle and structure of cholesteric liquid crystal display technology and concludes features and requirements of reflective type of electronic whiteboard based on cholesteric liquid crystal display technology. The design of drive circuit of reflective type of electronic whiteboard; the make-up of large reflective type of cholesteric liquid crystal homogeneous display screen as the display equipment of electronic whiteboard; and the adoption of C language to edi...

  18. Photoelectrochemical cells based on In2S3 single crystals

    International Nuclear Information System (INIS)

    The single crystals of tetragonal modification t-In2S3 are grown by the planar crystallization of the melt. On their basis, the photosensitive H2O/t-In2S3 cells are fabricated, and the spectra of their quantum efficiency are investigated. The broadband photosensivity of H2O/t-In2S3 cells is determined. On the basis of the photosensivity spectra, the character of interband transitions and the t-In2S3 band gaps corresponding to them are determined. The possibility of using the t-In2S3 crystals in broadband photoconverters of natural and polarized radiations is shown. The relation between the energy spectrum and the phase state of In2S3 crystals is revealed.

  19. Magnetic field sensor based on selectively magnetic fluid infiltrated dual-core photonic crystal fiber

    Science.gov (United States)

    Gangwar, Rahul Kumar; Bhardwaj, Vanita; Singh, Vinod Kumar

    2016-02-01

    We reported the modeling result of selectively magnetic fluid infiltrated dual-core photonic crystal fiber based magnetic field sensor. Inside the cross-section of the designed photonic crystal fiber, the two fiber cores filled with magnetic fluid (Fe3O4) form two independent waveguides with mode coupling. The mode coupling under different magnetic field strengths is investigated theoretically. The sensitivity of the sensor as a function of the structural parameters of the photonic crystal fiber is calculated. The result shows that the proposed sensing device with 1 cm photonic crystal fiber length has a large sensitivity of 305.8 pm/Oe.

  20. PCAM: a multi-user facility-based protein crystallization apparatus for microgravity

    Science.gov (United States)

    Carter, Daniel C.; Wright, Brenda; Miller, Teresa; Chapman, Jenny; Twigg, Pam; Keeling, Kim; Moody, Kerry; White, Melissa; Click, James; Ruble, John R.; Ho, Joseph X.; Adcock-Downey, Lawana; Dowling, Tim; Chang, Chong-Hwan; Ala, Paul; Rose, John; Wang, B. C.; Declercq, Jean-Paul; Evrard, Christine; Rosenberg, John; Wery, Jean-Pierre; Clawson, David; Wardell, Mark; Stallings, W.; Stevens, A.

    1999-01-01

    A facility-based protein crystallization apparatus for microgravity (PCAM) has been constructed and flown on a series of Space Shuttle Missions. The hardware development was undertaken largely because of the many important examples of quality improvements gained from crystal growth in the diffusion-limited environment in space. The concept was based on the adaptation for microgravity of a commonly available crystallization tray to increase sample density, to facilitate co-investigator participation and to improve flight logistics and handling. A co-investigator group representing scientists from industry, academia, and government laboratories has been established. Microgravity applications of the hardware have produced improvements in a number of structure-based crystallographic studies and include examples of enabling research. Additionally, the facility has been used to support fundamental research in protein crystal growth which has delineated factors contributing to the effect of microgravity on the growth and quality of protein crystals.

  1. A region segmentation based algorithm for building crystal position lookup table in scintillation detector

    CERN Document Server

    Wang, Hai Peng; Liu, Shuang Quan; Fan, Xin; Cao, Xue Xiang; Chai, Pei; Shan, Bao Ci

    2014-01-01

    In scintillation detector, scintillation crystals are typically made into 2-dimension modular array. The location of incident gamma-ray need be calibrated due to spatial response nonlinearity. Generally, position histograms, the characteristic flood response of scintillation detectors, are used for position calibration. In this paper, a position calibration method based on crystal position lookup table which maps the inaccurate location calculated by Anger logic to the exact hitting crystal position has been proposed, Firstly, position histogram is segmented into disconnected regions. Then crystal marking points are labeled by finding the centroids of regions. Finally, crystal boundaries are determined and crystal position lookup table is generated. The scheme is evaluated by the whole-body PET scanner and breast dedicated SPECT detector developed by Institute of High Energy Physics, Chinese Academy of Sciences. The results demonstrate that the algorithm is accurate, efficient, robust and general purpose.

  2. A research of weak absorption measurements in crystal based on photothermal interferometry

    Science.gov (United States)

    Chen, Bing; Liu, Zongkai; Wang, Shiwu

    2013-07-01

    It is important for testing the process of crystal growing and crystal quality. This paper built a mathematical model based on principle of photothermal common-path interferometry, the index change induced in the crystal by the heating pump beam and the phase distortion of probe beam in the heated area are presented then obtain the intensity distribution of the interference in the near filed. Optical geometry of focusing pump beam and intersecting pump and probe beams at waist position of the pump beam is used. This optical instruction can be adjusted easily and stabilized. Now CRYSTECH have the largest NLO crystals product line in the world, especially KTP crystals. With absorption measurements in nonlinear laser crystal KTP as an example to investigate the experimental parameters affecting the photothermal interference signal and high measuring precision. The analysis of experimental data showed this kind of instruction can reach the measurement accuracy of 0.1ppm.

  3. Light scattering in opal-based photonic crystals

    Science.gov (United States)

    Limonov, M. F.

    2010-05-01

    We present a new light scattering pattern in low-contrast opal-based photonic crystals (PhCs). The structure of real opals is always imperfect because of the a-SiO2 particles being inherently inhomogeneous and nonuniform in size and average dielectric permittivity. We found that opals possess all predictable properties of multi-component PhCs, which we define as periodic structures consisting of inhomogeneous or multiple (three or more) components. By theory, by properly tuning the permittivity of one of the components in ordered, low-contrast multi-component PhCs (for instance, of the filler ɛf in an opal), one can produce selective disappearance of any non-resonant (hkl) stop band. A study of transmission spectra of opals revealed that stop bands exhibit different (including resonant) behavior under variation of ɛf. Experiment did not, however, substantiate complete disappearance of stop bands predicted by theory for an ordered PhC. In the region of the predicted disappearance, a new effect has been observed, namely flip-over of the Bragg band, i.e., transformation of the Bragg dip into a Bragg rise. The flip-over effect, which has been studied in considerable detail in the particular example of the (111) stop band, originates from the nonuniformity of a-SiO2 particles. This nonuniformity leads to additional broad-band light scattering, the character of which is determined by Mie scattering. Thus, Mie scattering is responsible for two components in opal transmission spectra, more specifically, narrow Bragg bands and broad-band background. Their interference gives rise to formation of the Fano resonance, which in opal spectra becomes manifest, first, in a Bragg band asymmetry, and, second, in the flip-over effect, i.e., transformation of a photonic stop band into a photonic pass band.

  4. Proposal of highly sensitive optofluidic sensors based on dispersive photonic crystal waveguides

    DEFF Research Database (Denmark)

    Xiao, Sanshui; Mortensen, Niels Asger

    2007-01-01

    Optofluidic sensors based on highly dispersive two-dimensional photonic crystal waveguides are studied theoretically. Results show that these structures are strongly sensitive to the refractive index of the infiltrated liquid (nl), which is used to tune dispersion of the photonic crystal waveguid...

  5. Single-crystal organic field-effect transistors based on dibenzo-tetrathiafulvalene

    NARCIS (Netherlands)

    Mas-Torrent, M.; Hadley, P.; Bromley, S.T.; Crivillers, N.; Veciana, J.; Rovira, C.

    2004-01-01

    We report on the fabrication and characterization of field-effect transistors based on single crystals of the organic semiconductor dibenzo-tetrathiafulvalene (DB-TTF). We demonstrate that it is possible to prepare very-good-quality DB-TTF crystals from solution. These devices show high field-effect

  6. InP-based two-dimensional photonic crystals filled with polymers

    CERN Document Server

    Van der Heijden, R W; Snijders, J A P; Van der Heijden, R W; Karouta, F; Nötzel, R; Salemink, H W M; Kjellander, B K C; Bastiaansen, C W M; Broer, D J; Van der Drift, E

    2006-01-01

    Polymer filling of the air holes of Indium Phosphide based two-dimensional photonic crystals is reported. After infiltration of the holes with a liquid monomer and solidification of the infill in situ by thermal polymerization, complete filling is proven using scanning electron microscopy. Optical transmission measurements of a filled photonic crystal structure exhibit a redshift of the air band, confirming the complete filling.

  7. Anhydrous crystals of DNA bases are wide gap semiconductors

    Science.gov (United States)

    Maia, F. F.; Freire, V. N.; Caetano, E. W. S.; Azevedo, D. L.; Sales, F. A. M.; Albuquerque, E. L.

    2011-05-01

    We present the structural, electronic, and optical properties of anhydrous crystals of DNA nucleobases (guanine, adenine, cytosine, and thymine) found after DFT (Density Functional Theory) calculations within the local density approximation, as well as experimental measurements of optical absorption for powders of these crystals. Guanine and cytosine (adenine and thymine) anhydrous crystals are predicted from the DFT simulations to be direct (indirect) band gap semiconductors, with values 2.68 eV and 3.30 eV (2.83 eV and 3.22 eV), respectively, while the experimentally estimated band gaps we have measured are 3.83 eV and 3.84 eV (3.89 eV and 4.07 eV), in the same order. The electronic effective masses we have obtained at band extremes show that, at low temperatures, these crystals behave like wide gap semiconductors for electrons moving along the nucleobases stacking direction, while the hole transport are somewhat limited. Lastly, the calculated electronic dielectric functions of DNA nucleobases crystals in the parallel and perpendicular directions to the stacking planes exhibit a high degree of anisotropy (except cytosine), in agreement with published experimental results.

  8. Programmable agile beam steering based on a liquid crystal prism

    International Nuclear Information System (INIS)

    To meet the application need for agile precision beam steering, a novel liquid crystal prism device with a simple structure, convenient control, low cost and applicable performance is presented, and analysed theoretically and experimentally. The relationships between the optical path and the thickness of the liquid crystal cell under different voltages are investigated quantitatively by using a theoretical model. Analysis results show that the optical path profile of the liquid crystal prism has a quasi-linear slope and the standard deviation of the linear slope is less than 16 nm. The slope ratio can be changed by a voltage, which achieves the programmable beam steering and control. Practical liquid crystal prism devices are fabricated. Their deflection angles and wavefront profiles with different voltages are experimentally tested. The results are in good agreement with the simulated results. The results imply that the agile beam steering in a scope of 100 μrad with a micro-rad resolution is substantiated in the device. The two-dimensional beam steering is also achieved by cascading two liquid crystal prism devices. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  9. Black Phosphorus based One-dimensional Photonic Crystals and Microcavities

    CERN Document Server

    Kriegel, I

    2016-01-01

    The latest achievements in the fabrication of black phosphorus thin layers, towards the technological breakthrough of a phosphorene atomically thin layer, are paving the way for a their employment in electronics, optics, and optoelectronics. In this work, we have simulated the optical properties of one-dimensional photonic structures, i.e. photonic crystals and microcavities, in which few-layer black phosphorus is one of the components. The insertion of the 5 nm black phosphorous layers leads to a photonic band gap in the photonic crystals and a cavity mode in the microcavity interesting for light manipulation and emission enhancement.

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

    Institute of Scientific and Technical Information of China (English)

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

    2007-01-01

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

  11. Crystallization Kinetics of Misch Metal Based Bulk Metallic Glasses

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The crystallization kinetics of Mm55Al25Cu10Ni5Co5 bulk metallic glass (BMG) was investigated by means of differential scanning calorimetry (DSC) in the mode of continuous heating or isothermal annealing. It was found that the apparent activation energy Eg, Ex and Ep of the BMG calculated by Kissinger's method were 189.58, 170.68 and 170.41 kJ·mol-1, respectively, which was bigger than those of La55Al25Cu10Ni5Co5 BMG indicating that thermal stability of the former was higher than that of the latter. The local activation energy obtained using Ozawa equation decreased as crystallization proceeded except for the initial stage. The Avrami exponents were calculated to be in the range of 3.26~5.23 for different crystallization stages and isothermal temperatures. This implied that crystallization of Mm55Al25Cu10Ni5Co5 BMG was governed by diffusion-controlled three-dimensional growth with either reduced or increased nucleation rate, depending on isothermal temperature. Inconsistency of thermal stability with glass-forming ability for Mm(La)-Al-Cu-Ni-Co BMGs was discussed.

  12. Goniometer-based femtosecond X-ray diffraction of mutant 30S ribosomal subunit crystals

    Directory of Open Access Journals (Sweden)

    E. Han Dao

    2015-07-01

    Full Text Available In this work, we collected radiation-damage-free data from a set of cryo-cooled crystals for a novel 30S ribosomal subunit mutant using goniometer-based femtosecond crystallography. Crystal quality assessment for these samples was conducted at the X-ray Pump Probe end-station of the Linac Coherent Light Source (LCLS using recently introduced goniometer-based instrumentation. These 30S subunit crystals were genetically engineered to omit a 26-residue protein, Thx, which is present in the wild-type Thermus thermophilus 30S ribosomal subunit. We are primarily interested in elucidating the contribution of this ribosomal protein to the overall 30S subunit structure. To assess the viability of this study, femtosecond X-ray diffraction patterns from these crystals were recorded at the LCLS during a protein crystal screening beam time. During our data collection, we successfully observed diffraction from these difficult-to-grow 30S ribosomal subunit crystals. Most of our crystals were found to diffract to low resolution, while one crystal diffracted to 3.2 Å resolution. These data suggest the feasibility of pursuing high-resolution data collection as well as the need to improve sample preparation and handling in order to collect a complete radiation-damage-free data set using an X-ray Free Electron Laser.

  13. Study of the photonic crystal waveguide based on 2D compound lattice structure

    Institute of Scientific and Technical Information of China (English)

    WU Chao-jun; LI Yan-ping; WANG Zi-u

    2009-01-01

    group velocity dispersion compensation can be realized by the structure optimization. The results provide a reference for the study and application of photonic crystal waveguide based on the compound lattice structure.

  14. Kinetics of Non-Isothermal Crystallization of Coconut-based Cholesteryl Ester: Avrami and Ozawa Approache

    Directory of Open Access Journals (Sweden)

    J. F. Joson

    2003-06-01

    Full Text Available Kinetics of non-isothermal crystallization of coconut-based cholesteryl ester was performed by differentialscanning calorimetry under various heating rates. Different analysis methods were used to describe theprocess of non-isothermal crystallization. The results showed that the Avrami equation could describe thesystem very well. However, the Ozawa analysis failed. A probable reason is the difference in the crystallizationkinetics at high and low relative crystallization. The phase transitions of the coconut-based cholesterylester were also observed through optical polarizing microscopy

  15. An ARROW-based silicon-on-insulator photonic crystal waveguides with reduced losses

    DEFF Research Database (Denmark)

    Lavrinenko, Andrei

    2006-01-01

    We employ an antiresonant reflecting layers arrangement for siliicon-on-insulator based photonic crystal waveguides with thin cores. 3D FDTD numerical modelling reveals the reduction of losses with a promising potential for competing with membrane-like waveguides.......We employ an antiresonant reflecting layers arrangement for siliicon-on-insulator based photonic crystal waveguides with thin cores. 3D FDTD numerical modelling reveals the reduction of losses with a promising potential for competing with membrane-like waveguides....

  16. Photonic Crystals: Enhancing the Light Output of Scintillation Based Detectors

    CERN Document Server

    Knapitsch, Arno Richard

    A scintillator is a material which emits light when excited by ionizing radiation. Such materials are used in a diverse range of applications; From high energy particle physics experiments, X-ray security, to nuclear cameras or positron emission tomography. Future high-energy physics (HEP) experiments as well as next generation medical imaging applications are more and more pushing towards better scintillation characteristics. One of the problems in heavy scintillating materials is related to their high index of refraction. As a consequence, most of the scintillation light produced in the bulk material is trapped inside the crystal due to total internal reflection. The same problem also occurs with light emitting diodes (LEDs) and has for a long time been considered as a limiting factor for their overall efficiency. Recent developments in the area of nanophotonics were showing now that those limitations can be overcome by introducing a photonic crystal (PhC) slab at the outcoupling surface of the substrate. P...

  17. Ultra-compact photonic crystal based water temperature sensor

    Science.gov (United States)

    Nikoufard, Mahmoud; Kazemi Alamouti, Masoud; Adel, Alireza

    2016-09-01

    We design an ultra-compact water temperature sensor by using the photonic crystal technology on the InP substrate at the 1.55-μm wavelength window. The photonic crystal consists of rods in a hexagonal lattice and a polymethyl methacrylate (PMMA) background. By using the plane wave expansion (PWE) method, the lattice constant and radius of rods are obtained, 520 nm and 80.6 nm, respectively. With a nanocavity placed in the waveguide, a resonance peak is observed at the 1.55-μm wavelength window. Any change of the water temperature inside the nanocavity results in the shift of the resonance wavelength. Our simulations show a shift of about 11 nm for a temperature change of 22.5 ℃. The resonance wavelength has a linear relation with the water temperature.

  18. Solution based synthesis of simple fcc Si nano-crystals under ambient conditions.

    Science.gov (United States)

    Balcı, Mustafa H; Sæterli, Ragnhild; Maria, Jerome; Lindgren, Mikael; Holmestad, Randi; Grande, Tor; Einarsrud, Mari-Ann

    2013-02-28

    We demonstrate for the first time that simple face-centered cubic (fcc) silicon nano-crystals can be produced by a solution based bottom-up synthesis route under ambient conditions. Simple fcc Si nano-crystals (2-7 nm) were prepared at room temperature by using sodium cyclopentadienide as a reducing agent for silicon tetrachloride. Photoluminescence emission at 550 nm was observed for the fcc silicon nano-crystals upon excitation at 340 nm, indicating that fcc Si nano-crystals were exhibiting direct bandgap like semiconductor properties with very fast radiative recombination rates. The new synthesis route makes possible the production and study of simple fcc polymorphs of Si nano-crystals with an easy alteration of surface termination groups.

  19. Electronically Reconfigurable Liquid Crystal Based Mm-Wave Polarization Converter

    OpenAIRE

    Doumanis, E.; Goussetis, G.; Dickie, R.; CAHILL, R; Baine, P; Bain, M; V. Fusco; Encinar, J. A.; Toso, G

    2014-01-01

    An electronically tunable reflection polarizer which exploits the dielectric anisotropy of nematic liquid crystals (LC) has been designed, fabricated and measured in a frequency band centered at 130 GHz. The phase agile polarizing mirror converts an incident slant 45° signal upon reflection to right hand circular (RHCP), orthogonal linear (-45 °) or left hand circular (LHCP) polarization depending on the value of the voltage biasing the LC mixture. In the experimental set-up this is achieved ...

  20. Photonic Crystal Fiber Temperature Sensor Based on Quantum Dot Nanocoatings

    Directory of Open Access Journals (Sweden)

    Beatriz Larrión

    2009-01-01

    Full Text Available Quantum dot nanocoatings have been deposited by means of the Layer-by-Layer technique on the inner holes of Photonic Crystal Fibers (PCFs for the fabrication of temperature sensors. The optical properties of these sensors including absorbance, intensity emission, wavelength of the emission band, and the full width at half maximum (FWHM have been experimentally studied for a temperature range from −40 to 70C°.

  1. A Double Emulsion-Based, Plastic-Glass Hybrid Microfluidic Platform for Protein Crystallization

    Directory of Open Access Journals (Sweden)

    Deyong Zhu

    2015-10-01

    Full Text Available This paper reports the design and construction of a plastic-glass hybrid microfluidic platform for performing protein crystallization trials in nanoliter double emulsions. The double emulsion-based protein crystallization trials were implemented with both the vapor-diffusion method and microbatch method by controlling the diffusion of water between the inner and outer phases and by eliminating water evaporation. Double emulsions, whose inner and outer environments can be easily adjusted, can provide ideal conditions to explore protein crystallization with the advantages of a convection-free environment and a homogeneous interface. The property of the water-oil interface was demonstrated to be a critical factor for nucleation, and appropriate surfactants should be chosen to prevent protein adsorption at the interface. The results from the volume effect study showed a trend of fewer crystals and longer incubation time when the protein solution volume became smaller, suggesting that the nucleation in protein crystallization process can be controlled by changing the volume of protein solutions. Finally, sparse matrix screening was achieved using the double emulsion-based microbatch method. The double emulsion-based approach for protein crystallization is a promising tool for enhancing the crystal quality by controlling the nucleation process.

  2. Transparent nematic phase in a liquid-crystal-based microemulsion.

    Science.gov (United States)

    Yamamoto, J; Tanaka, H

    2001-01-18

    Complex fluids are usually produced by mixing together several distinct components, the interactions between which can give rise to unusual optical and rheological properties of the system as a whole. For example, the properties of microemulsions (composed of water, oil and surfactants) are determined by the microscopic structural organization of the fluid that occurs owing to phase separation of the component elements. Here we investigate the effect of introducing an additional organizing factor into such a fluid system, by replacing the oil component of a conventional water-in-oil microemulsion with an intrinsically anisotropic fluid--a nematic liquid crystal. As with the conventional case, the fluid phase-separates into an emulsion of water microdroplets (stabilized by the surfactant as inverse micelles) dispersed in the 'oil' phase. But the properties are further influenced by a significant directional coupling between the liquid-crystal molecules and the surfactant tails that emerge (essentially radially) from the micelles. The result is a modified bulk-liquid crystal that is an ordered nematic at the mesoscopic level, but which does not exhibit the strong light scattering generally associated with bulk nematic order: the bulk material here is essentially isotropic and thus transparent.

  3. Liquid crystal alignment in electro-responsive nanostructured thermosetting materials based on block copolymer dispersed liquid crystal

    International Nuclear Information System (INIS)

    Novel well-defined nanostructured thermosetting systems were prepared by modification of a diglicydylether of bisphenol-A epoxy resin (DGEBA) with 10 or 15 wt% amphiphilic poly(styrene-b-ethylene oxide) block copolymer (PSEO) and 30 or 40 wt% low molecular weight liquid crystal 4'-(hexyl)-4-biphenyl-carbonitrile (HBC) using m-xylylenediamine (MXDA) as a curing agent. The competition between well-defined nanostructured materials and the ability for alignment of the liquid crystal phase in the materials obtained has been studied by atomic and electrostatic force microscopy, AFM and EFM, respectively. Based on our knowledge, this is the first time that addition of an adequate amount (10 wt%) of a block copolymer to 40 wt% HBC-(DGEBA/MXDA) leads to a well-organized nanostructured thermosetting system (between a hexagonal and worm-like ordered structure), which is also electro-responsive with high rate contrast. This behavior was confirmed using electrostatic force microscopy (EFM), by means of the response of the HBC liquid crystal phase to the voltage applied to the EFM tip. In contrast, though materials containing 15 wt% PSEO and 30 wt% HBC also form a well-defined nanostructured thermosetting system, they do not show such a high contrast between the uncharged and charged surface

  4. A flow-free droplet-based device for high throughput polymorphic crystallization.

    Science.gov (United States)

    Yang, Shih-Mo; Zhang, Dapeng; Chen, Wang; Chen, Shih-Chi

    2015-06-21

    Crystallization is one of the most crucial steps in the process of pharmaceutical formulation. In recent years, emulsion-based platforms have been developed and broadly adopted to generate high quality products. However, these conventional approaches such as stirring are still limited in several aspects, e.g., unstable crystallization conditions and broad size distribution; besides, only simple crystal forms can be produced. In this paper, we present a new flow-free droplet-based formation process for producing highly controlled crystallization with two examples: (1) NaCl crystallization reveals the ability to package saturated solution into nanoliter droplets, and (2) glycine crystallization demonstrates the ability to produce polymorphic crystallization forms by controlling the droplet size and temperature. In our process, the saturated solution automatically fills the microwell array powered by degassed bulk PDMS. A critical oil covering step is then introduced to isolate the saturated solution and control the water dissolution rate. Utilizing surface tension, the solution is uniformly packaged in the form of thousands of isolating droplets at the bottom of each microwell of 50-300 μm diameter. After water dissolution, individual crystal structures are automatically formed inside the microwell array. This approach facilitates the study of different glycine growth processes: α-form generated inside the droplets and γ-form generated at the edge of the droplets. With precise temperature control over nanoliter-sized droplets, the growth of ellipsoidal crystalline agglomerates of glycine was achieved for the first time. Optical and SEM images illustrate that the ellipsoidal agglomerates consist of 2-5 μm glycine clusters with inner spiral structures of ~35 μm screw pitch. Lastly, the size distribution of spherical crystalline agglomerates (SAs) produced from microwells of different sizes was measured to have a coefficient variation (CV) of less than 5%, showing

  5. Nucleation and crystallization of tailing-based glass-ceramics by microwave heating

    Institute of Scientific and Technical Information of China (English)

    Bao-wei Li; Hong-xia Li; Xue-feng Zhang; Xiao-lin Jia; Zhi-chao Sun

    2015-01-01

    The effect of microwave radiation on the nucleation and crystallization of tailing-based glass-ceramics was investigated using a 2.45 GHz multimode microwave cavity. Tailing-based glass samples were prepared from Shandong gold tailings and Guyang iron tailings utilizing a conventional glass melting technique. For comparison, the tailing-based glass samples were crystallized using two different heat-treatment meth-ods:conventional heating and hybrid microwave heating. The nucleation and crystallization temperatures were determined by performing a dif-ferential thermal analysis of the quenched tailing-based glass. The prepared glass-ceramic samples were further characterized by Fourier trans-form infrared spectroscopy, X-ray diffraction, Raman spectroscopy, thermal expansion coefficient measurements, and scanning electron micros-copy. The results demonstrated that hybrid microwave heating could be successfully used to crystallize the tailing-based glass, reduce the proc-essing time, and decrease the crystallization temperature. Furthermore, the results indicated that the nucleation and crystallization mechanism of the hybrid microwave heating process slightly differs from that of the conventional heating process.

  6. Nucleation and crystallization of tailing-based glass-ceramics by microwave heating

    Science.gov (United States)

    Li, Bao-wei; Li, Hong-xia; Zhang, Xue-feng; Jia, Xiao-lin; Sun, Zhi-chao

    2015-12-01

    The effect of microwave radiation on the nucleation and crystallization of tailing-based glass-ceramics was investigated using a 2.45 GHz multimode microwave cavity. Tailing-based glass samples were prepared from Shandong gold tailings and Guyang iron tailings utilizing a conventional glass melting technique. For comparison, the tailing-based glass samples were crystallized using two different heat-treatment methods: conventional heating and hybrid microwave heating. The nucleation and crystallization temperatures were determined by performing a differential thermal analysis of the quenched tailing-based glass. The prepared glass-ceramic samples were further characterized by Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, thermal expansion coefficient measurements, and scanning electron microscopy. The results demonstrated that hybrid microwave heating could be successfully used to crystallize the tailing-based glass, reduce the processing time, and decrease the crystallization temperature. Furthermore, the results indicated that the nucleation and crystallization mechanism of the hybrid microwave heating process slightly differs from that of the conventional heating process.

  7. High-Efficiency Nitride-Base Photonic Crystal Light Sources

    Energy Technology Data Exchange (ETDEWEB)

    James Speck; Evelyn Hu; Claude Weisbuch; Yong-Seok Choi; Kelly McGroddy; Gregor Koblmuller; Elison Matioli; Elizabeth Rangel; Fabian Rol; Dobri Simeonov

    2010-01-31

    The research activities performed in the framework of this project represent a major breakthrough in the demonstration of Photonic Crystals (PhC) as a competitive technology for LEDs with high light extraction efficiency. The goals of the project were to explore the viable approaches to manufacturability of PhC LEDS through proven standard industrial processes, establish the limits of light extraction by various concepts of PhC LEDs, and determine the possible advantages of PhC LEDs over current and forthcoming LED extraction concepts. We have developed three very different geometries for PhC light extraction in LEDs. In addition, we have demonstrated reliable methods for their in-depth analysis allowing the extraction of important parameters such as light extraction efficiency, modal extraction length, directionality, internal and external quantum efficiency. The information gained allows better understanding of the physical processes and the effect of the design parameters on the light directionality and extraction efficiency. As a result, we produced LEDs with controllable emission directionality and a state of the art extraction efficiency that goes up to 94%. Those devices are based on embedded air-gap PhC - a novel technology concept developed in the framework of this project. They rely on a simple and planar fabrication process that is very interesting for industrial implementation due to its robustness and scalability. In fact, besides the additional patterning and regrowth steps, the process is identical as that for standard industrially used p-side-up LEDs. The final devices exhibit the same good electrical characteristics and high process yield as a series of test standard LEDs obtained in comparable conditions. Finally, the technology of embedded air-gap patterns (PhC) has significant potential in other related fields such as: increasing the optical mode interaction with the active region in semiconductor lasers; increasing the coupling of the incident

  8. Nanomechanics of cellulose crystals and cellulose-based polymer composites

    Science.gov (United States)

    Pakzad, Anahita

    Cellulose-polymer composites have potential applications in aerospace and transportation areas where lightweight materials with high mechanical properties are needed. In addition, these economical and biodegradable composites have been shown to be useful as polymer electrolytes, packaging structures, optoelectronic devices, and medical implants such as wound dressing and bone scaffolds. In spite of the above mentioned advantages and potential applications, due to the difficulties associated with synthesis and processing techniques, application of cellulose crystals (micro and nano sized) for preparation of new composite systems is limited. Cellulose is hydrophilic and polar as opposed to most of common thermoplastics, which are non-polar. This results in complications in addition of cellulose crystals to polymer matrices, and as a result in achieving sufficient dispersion levels, which directly affects the mechanical properties of the composites. As in other composite materials, the properties of cellulose-polymer composites depend on the volume fraction and the properties of individual phases (the reinforcement and the polymer matrix), the dispersion quality of the reinforcement through the matrix and the interaction between CNCs themselves and CNC and the matrix (interphase). In order to develop economical cellulose-polymer composites with superior qualities, the properties of individual cellulose crystals, as well as the effect of dispersion of reinforcements and the interphase on the properties of the final composites should be understood. In this research, the mechanical properties of CNC polymer composites were characterized at the macro and nano scales. A direct correlation was made between: - Dispersion quality and macro-mechanical properties - Nanomechanical properties at the surface and tensile properties - CNC diameter and interphase thickness. Lastly, individual CNCs from different sources were characterized and for the first time size-scale effect on

  9. A switchable circular polarizer based on zenithal bistable liquid crystal gratings

    Science.gov (United States)

    Zografopoulos, Dimitrios C.; Isić, Goran; Kriezis, Emmanouil E.; Beccherelli, Romeo

    2016-05-01

    A switchable circular polarizer for infrared telecom wavelengths based on zenithal bistable liquid crystal gratings is designed and investigated by employing the finite-element method for the study of full-wave light propagation and a tensorial formulation for the liquid crystal orientation. The handedness of the output circular polarization can be selected by switching between the two stable states of the liquid-crystal grating. Analysis of the spectral dependence and the tolerance of the polarizer’s performance with respect to deviations from the optimized geometry reveals the robustness of its polarizing properties, which stems from the non-resonant nature of its operation.

  10. Single crystal growth of europium and ytterbium based intermetallic compounds using metal flux technique

    Indian Academy of Sciences (India)

    Sumanta Sarkar; Sebastian C Peter

    2012-11-01

    This article covers the use of indium as a potential metal solvent for the crystal growth of europium and ytterbium-based intermetallic compounds. A brief view about the advantage of metal flux technique and the use of indium as reactive and non-reactive flux are outlined. Large single crystals of EuGe2, EuCoGe3 and Yb2AuGe3 compounds were obtained in high yield from the reactions of the elements in liquid indium. The results presented here demonstrate that considerable advances in the discovery of single crystal growth of complex phases are achievable utilizing molten metals as solvents.

  11. A Novel Microwave Tunable Band-Pass Filter Integrated Power Divider Based on Liquid Crystal

    Directory of Open Access Journals (Sweden)

    Yupeng Liu

    2015-01-01

    Full Text Available This paper proposes a novel microwave continuous adjustable band-pass filter integrated power divider based on nematic liquid crystals (LCs. The proposed power divider uses liquid crystal (LC as the dielectric material. It can realize phase shift by changing the dielectric anisotropy, when biasing the high anisotropy nematic liquid crystal. It is mainly used in microwave frequencies. It has a large number of advantages compared to conventional filter integrated power divider, such as low loss, multifunction integration, continuous adjustable, miniaturization, low processing costs, low operating voltage, high phase shift, and convenient manufacture. Therefore, it has shown great potential for application.

  12. Creating standard resistors based on germanium and silicon single crystals grown under microgravity conditions

    Science.gov (United States)

    Kartavykh, A. V.; Rakov, V. V.

    2006-11-01

    Requirements on the creation of standard resistors (SRs), which are necessary for the calibration of microprobe complexes used for the diagnostics of electrical homogeneity of single crystal semiconductors, are considered. SR prototypes have been created based on Sb-doped Ge single crystals grown by float zone melting under microgravity conditions aboard the Photon series satellites, in which the inhomogeneity of the resistivity distribution does not exceed 1%. The main factors influencing the homogeneity of doping for Ge and Si crystals grown from melt under orbital flight conditions are formulated; methods for the optimization of this technological process are described.

  13. SOLIDIFICATION OF NICKEL-BASED SINGLE CRYSTAL SUPERALLOY BY ELECTRIC FIELD

    Institute of Scientific and Technical Information of China (English)

    Y.S. Yang; X.H. Feng; G.F. Cheng; Y.J. Li; Z.Q. Hu

    2005-01-01

    The crystal growth of a nickel-based single crystal superalloy DD3 was researched via controlled directional solidification under the action of a DC electric field. The cellular or dendrite spacing of the single crystal superalloy is refined and microsegregation of alloying elements Al,Ti, Mo and W, is reduced by the electric field. The electric field decreases the interface stability and reduces the critical growth rate of the cellular-dendritic translation because of Thomson effect and Joule heating. The precipitation of the γ' phase is more uniform and the size of the γ'phase is smaller with the electric field than that without the electric field.

  14. Crystal chemistry of the perovskite based superconducting oxides

    International Nuclear Information System (INIS)

    The crystal chemistry of K2NiF4 and Ba2YCu3O7 type compounds is discussed. The composition dependence of the lattice parameters for the Ba2-xLaxYCu3O7+δ solid solution and of the oxygen stoichiometry in Ba2-xLaxYCu3O7+δ annealed in O2 at 500 C, as well as a tentative partial phase equilibria diagram for ABO3-x perovskites in the (Ba, La, Y) CuO3-x chemical system are given. 19 refs, 4 figs

  15. Faraday rotator based on TSAG crystal with orientation.

    Science.gov (United States)

    Yasuhara, Ryo; Snetkov, Ilya; Starobor, Aleksey; Mironov, Evgeniy; Palashov, Oleg

    2016-07-11

    A Faraday isolator (FI) for high-power lasers with kilowatt-level average power and 1-µm wavelength was demonstrated using a terbium scandium aluminum garnet (TSAG) with its crystal axis aligned in the direction. Furthermore, no compensation scheme for thermally induced depolarization in a magnetic field was used. An isolation ratio of 35.4 dB (depolarization ratio γ of 2.9 × 10-4) was experimentally observed at a maximum laser power of 1470 W. This result for room-temperature FIs is the best reported, and provides a simple, practical solution for achieving optical isolation in high-power laser systems. PMID:27410823

  16. Integrable microwave filter based on a photonic crystal delay line

    OpenAIRE

    Sancho Durá, Juan; Bourderionnet, Jerome; Lloret Soler, Juan Antonio; Combrie, Sylvain; Gasulla Mestre, Ivana; Xavier, Stephane; Sales Maicas, Salvador; Colman, Pierre; Lehoucq, Gaelle; Dolfi, Daniel; Capmany Francoy, José; Rossi, Alfredo

    2012-01-01

    The availability of a tunable delay line with a chip-size footprint is a crucial step towards the full implementation of integrated microwave photonic signal processors. Achieving a large and tunable group delay on a millimetre-sized chip is not trivial. Slow light concepts are an appropriate solution, if propagation losses are kept acceptable. Here we use a low-loss 1.5 mm-long photonic crystal waveguide to demonstrate both notch and band-pass microwave filters that can be tuned over the 0 5...

  17. Ellipsometric investigations of photonic crystals based on carbon nanofibers

    CERN Document Server

    Rehammar, R; Arwin, H; Kinaret, J M; Campbell, E E B

    2010-01-01

    Carbon nanofibers (CNF) are used as components of planar photonic crystals (PC). Square and rectangular lattices as well as random patterns of vertically aligned CNF were fabricated and their properties studied using ellipsometry. Conventional methods of ellipsometric analysis used in thin film ellipsometry are not applicable to these samples due to their nanostructured nature. We show that detailed information such as symmetry directions and the band structure of these novel materials can be extracted from considerations of the polarization state in the specular beam.

  18. Pulse-width compression based on photonic crystal fiber

    Institute of Scientific and Technical Information of China (English)

    WANG Jing; WANG Zhen-li; SHI Yan-mei

    2006-01-01

    According to the characteristics of high-order solitons,compressed picosecond pulses are numerically simulated in the photonic crystal fiber (PCF),by means of split-step Fourier method. The results show that,PCF enables input pulse with lower peak power to form high-order solitons for the purpose of femtosecond pulse-width compression. For example,60- femtosecond pulse width was made for 1-ps initial pulse width only over the distance of 2.2 m.Besides,shorter optimum fiber length for compression and higher compression ratio could be obtained on the premise of pre-chirp technique.

  19. Optical switch based on the electrically controlled liquid crystal interface.

    Science.gov (United States)

    Komar, Andrei A; Tolstik, Alexei L; Melnikova, Elena A; Muravsky, Alexander A

    2015-06-01

    The peculiarities of the linearly polarized light beam reflection at the interface within the bulk of a nematic liquid crystal (NLC) cell with different orientations of the director are analyzed. Two methods to create the interface are considered. Combination of the planar and homeotropic orientations of the NLC director is realized by means of a spatially structured electrode under the applied voltage. In-plane patterned azimuthal alignment of the NLC director is created by the patterned rubbing alignment technique. All possible orthogonal orientations of the LC director are considered; the configurations for realization of total internal reflection are determined. The revealed relationship between the propagation of optical beams in a liquid crystal material and polarization of laser radiation has enabled realization of the spatial separation for the orthogonally polarized light beams at the interface between two regions of NLC with different director orientations (domains). Owing to variations in the applied voltage and, hence, in the refractive index gradient, the light beam propagation directions may be controlled electrically. PMID:26192675

  20. Formulation and solid state characterization of nicotinamide-based co-crystals of fenofibrate

    Directory of Open Access Journals (Sweden)

    Sheetal Shewale

    2015-01-01

    Full Text Available The present investigation deals with formulation of nicotinamide-based co-crystals of fenofibrate by different methods and solid-state characterization of the prepared co-crystals. Fenofibrate and nicotinamide as a coformer in 1:1 molar ratio were used to formulate molecular complexes by kneading, solution crystallization, antisolvent addition and solvent drop grinding methods. The prepared molecular complexes were characterized by powder X-ray diffractometry, differential scanning calorimetry, Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy and in vitro dissolution study. Considerable improvement in the dissolution rate of fenofibrate from optimized co-crystal formulation was due to an increased solubility that is attributed to the super saturation from the fine co-crystals is faster because of large specific surface area of small particles and prevention of phase transformation to pure fenofibrate. In vitro dissolution study showed that the formation of co-crystals improves the dissolution rate of fenofibrate. Nicotinamide forms the co-crystals with fenofibrate, theoretically and practically.

  1. Microstructural observations of the crystallization of amorphous Fe-Si-B based magnetic alloys

    International Nuclear Information System (INIS)

    The effect of Cu and Nb alloying additions on the crystallization of Fe-Si-B based alloys were studied. DSC, XRD, TEM, EELS and VSM techniques were used to study the thermal properties, phase formation during primary crystallization, morphological transitions and magnetic properties. The additions of individual Cu or Nb alloying additions changed the crystallization temperature as well as the activation energy for primary crystallization. The phases formed during primary crystallization for the Fe77.5Si13.5B9, Fe76.5Si13.5B9Cu1 and Fe74.5Si13.5B9Nb3Cu1 alloys are the same, however the morphologies are significantly different. Alloying additions of 3 at.% Nb induced a change in the crystallization mechanism and the type of phases formed. The combined additions of Cu and Nb resulted in the formation of nanocrystals. B atoms were found to be rejected around dendrites formed during primary crystallization of the Fe77.5Si13.5B9 alloy. The highest saturation magnetization and the lowest coercivity is obtained in the Fe77.5Si13.5B9 and Fe74.5Si13.5B9Nb3Cu1 alloy respectively after annealing at 550 deg. C for 1 h

  2. Compressive sensing spectrometry based on liquid crystal devices.

    Science.gov (United States)

    August, Yitzhak; Stern, Adrian

    2013-12-01

    We present a new type of compressive spectroscopy technique employing a liquid crystal (LC) phase retarder. A tunable LC cell is used in a manner compliant with the compressive sensing (CS) framework to significantly reduce the spectral scanning effort. The presented optical spectrometer consists of a single LC phase retarder combined with a single photo detector, where the LC phase retarder is used to modulate the input spectrum and the photodiode is used to measure the transmitted spectral signal. Sequences of measurements are taken, where each measurement is done with a different state of the retarder. Then, the set of photodiode measurements is used as input data to a CS solver algorithm. We demonstrate numerally compressive spectral sensing with approximately ten times fewer measurements than with an equivalent conventional spectrometer.

  3. Photonic crystal fiber half-taper probe based refractometer.

    Science.gov (United States)

    Wang, Pengfei; Ding, Ming; Bo, Lin; Guan, Chunying; Semenova, Yuliya; Sun, Weimin; Yuan, Libo; Brambilla, Gilberto; Farrell, Gerald

    2014-04-01

    A compact single-mode photonic crystal fiber single-mode fiber tip (SPST) refractive index sensor is demonstrated in this Letter. A CO2 laser cleaving technique is utilized to provide a clean-cut fiber tip, which is then coated by a layer of gold to increase reflection. An average sensitivity of 39.1 nm/RIU and a resolvable index change of 2.56×10(-4) are obtained experimentally with a ∼3.2 μm diameter SPST. The temperature dependence of this fiber-optic sensor probe is presented. The proposed SPST refractometer is also significantly less sensitive to temperature and an experimental demonstration of this reduced sensitivity is presented in the Letter. Because of its compactness, ease of fabrication, linear response, low temperature dependency, easy connectivity to other fiberized optical components and low cost, this refractometer could find various applications in chemical and biological sensing. PMID:24686678

  4. Advanced excimer-based crystallization systems for production solutions

    International Nuclear Information System (INIS)

    Line beam excimer laser annealing (ELA) is a well-known technique for thin Si-film crystallization and established in LTPS mass production. With introduction of sequential lateral solidification (SLS) some aspects such as crystalline quality, throughput and flexibility regarding the substrate size could be improved, but for OLED manufacturing still further process development is necessary. This paper discusses line beam ELA and SLS-techniques that might enable process engineers to make polycrystalline-silicon (poly-Si) films with a high degree of uniformity and quality as required for system on glass (SOG) and active matrix organic light emitting displays (AMOLED). Equipment requirements are discussed and compared to previous standards. SEM-images of process examples are shown in order to demonstrate the viability

  5. Advanced excimer-based crystallization systems for production solutions

    Energy Technology Data Exchange (ETDEWEB)

    Simon, F. [Lambda Physik AG, Goettingen (Germany)]. E-mail: frank.simon@coherent.com; Brune, J. [Lambda Physik AG, Goettingen (Germany); Herbst, L. [Lambda Physik AG, Goettingen (Germany)

    2006-04-30

    Line beam excimer laser annealing (ELA) is a well-known technique for thin Si-film crystallization and established in LTPS mass production. With introduction of sequential lateral solidification (SLS) some aspects such as crystalline quality, throughput and flexibility regarding the substrate size could be improved, but for OLED manufacturing still further process development is necessary. This paper discusses line beam ELA and SLS-techniques that might enable process engineers to make polycrystalline-silicon (poly-Si) films with a high degree of uniformity and quality as required for system on glass (SOG) and active matrix organic light emitting displays (AMOLED). Equipment requirements are discussed and compared to previous standards. SEM-images of process examples are shown in order to demonstrate the viability.

  6. Laser radiation frequency doubling in a single-crystal fibre based on a stoichiometric LiNbO{sub 3} crystal

    Energy Technology Data Exchange (ETDEWEB)

    Kashin, V V; Nikolaev, D A; Rusanov, S Ya; Tsvetkov, V B [A M Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

    2015-01-31

    We demonstrate the employment of single-crystal optical fibres based on lithium niobate for doubling the laser radiation frequency. The measured characteristics of the fibre confirm its high quality and spatial homogeneity. Parameters of the frequency doublers for neodymium laser radiation (λ = 1 mm) based on fibre and bulk single crystals are compared. Single crystals are grown by the method of laser-heated pedestal growing with heating by radiation of a CO{sub 2} laser (LHPG-method). (nonlinear optical phenomena)

  7. Investigation on the optical and electrical properties of MMTG crystal: A Lewis base adduct

    Science.gov (United States)

    Vetha Potheher, I.; Rajarajan, K.; Vimalan, M.; Tamilselvan, S.; Jeyasekaran, R.; Sagayaraj, P.

    2011-09-01

    The growth of nonlinear optical single crystal of manganese mercury thiocyanate glycol monomethyl ether (MMTG), a Lewis base adduct of manganese mercury thiocyanate (MMTC), is reported. MMTG crystallizes in orthorhombic structure with Pca2 1 space group. The optical band gap energy of the sample is found to be 3.5 eV. The sample is thermally stable up to 145 °C. The grown crystal is characterized by photoluminescence, dielectric, dc conductivity, photoconductivity and SEM studies. From the photoluminescence study, the suitability of the material for blue and green light generation is confirmed. The electric and dielectric response of the grown crystal is studied as a function of temperature and the results are discussed. The dc activation energy of the sample is found to be 0.048 eV.

  8. Analysis of Sampled Fiber Bragg Grating Based on the Photonic Crystal Theory

    Institute of Scientific and Technical Information of China (English)

    ZHU Dan-dan

    2009-01-01

    One of the most basic characteristics of photonic crystal is frequency band gap.When defects are introduced into the periodic photonic crystal,a number of defect modes appear in the stop band.In this paper,we exploit transfer matrix method based on photonic crystal theory,and assume the sampled fiber Bragg grating as one-dimensional dual photonic crystal with a large size defect.Characteristics of the sampled fiber Bragg grating are analyzed.Experimental results show that the sampled fiber Bragg grating has many reflective peaks.Its reflectivity,center wavelength,reflective peak intervals and band width all change with the grating parameters,including grating length,duty ratio of the material with high dielectric constant,and index modulation depth and period.Results agree with the conventional couple mode theory which can be used when analyzing other characteristics of the sampled fiber Bragg grating or applying it into practice.

  9. Tunable terahertz fishnet metamaterials based on thin nematic liquid crystal layers for fast switching.

    Science.gov (United States)

    Zografopoulos, Dimitrios C; Beccherelli, Romeo

    2015-08-14

    The electrically tunable properties of liquid-crystal fishnet metamaterials are theoretically investigated in the terahertz spectrum. A nematic liquid crystal layer is introduced between two fishnet metallic structures, forming a voltage-controlled metamaterial cavity. Tuning of the nematic molecular orientation is shown to shift the magnetic resonance frequency of the metamaterial and its overall electromagnetic response. A shift higher than 150 GHz is predicted for common dielectric and liquid crystalline materials used in terahertz technology and for low applied voltage values. Owing to the few micron-thick liquid crystal cell, the response speed of the tunable metamaterial is calculated as orders of magnitude faster than in demonstrated liquid-crystal based non-resonant terahertz components. Such tunable metamaterial elements are proposed for the advanced control of electromagnetic wave propagation in terahertz applications.

  10. Design, construction and testing of a system for detection of toxic gases based on piezoelectric crystals.

    Science.gov (United States)

    Leyva, J A; de Cisneros, J L; de Barreda, D G; Becerra, A J

    1994-01-01

    A system for static operation of toxic gas sensors based on piezoelectric crystals was constructed as a preliminary step in the development of this type of sensor. The sensing part of the setup consists of a twin oscillating circuit assembled from commercially available electronic parts mounted on a motherboard. The oscillating circuits can accommodate two piezoelectric crystals, of which one or both can be coated with different materials, or a single one, as required. The sensing assembly (crystals plus oscillating circuits) is placed in a customized test chamber that allows one to control and reproduce its internal environment. Once assembled and fine-tuned, the proposed setup was used to test a commercially available piezoelectric crystal for sensing formaldehyde in order to expand available information on this type of sensor. PMID:18965902

  11. High Performance Relaxor-Based Ferroelectric Single Crystals for Ultrasonic Transducer Applications

    Directory of Open Access Journals (Sweden)

    Yan Chen

    2014-07-01

    Full Text Available Relaxor-based ferroelectric single crystals Pb(Mg1/3Nb2/3O3-PbTiO3 (PMN-PT have drawn much attention in the ferroelectric field because of their excellent piezoelectric properties and high electromechanical coupling coefficients (d33~2000 pC/N, kt~60% near the morphotropic phase boundary (MPB. Ternary Pb(In1/2Nb1/2O3-Pb(Mg1/3Nb2/3O3-PbTiO3 (PIN-PMN-PT single crystals also possess outstanding performance comparable with PMN-PT single crystals, but have higher phase transition temperatures (rhombohedral to tetragonal Trt, and tetragonal to cubic Tc and larger coercive field Ec. Therefore, these relaxor-based single crystals have been extensively employed for ultrasonic transducer applications. In this paper, an overview of our work and perspectives on using PMN-PT and PIN-PMN-PT single crystals for ultrasonic transducer applications is presented. Various types of single-element ultrasonic transducers, including endoscopic transducers, intravascular transducers, high-frequency and high-temperature transducers fabricated using the PMN-PT and PIN-PMN-PT crystals and their 2-2 and 1-3 composites are reported. Besides, the fabrication and characterization of the array transducers, such as phased array, cylindrical shaped linear array, high-temperature linear array, radial endoscopic array, and annular array, are also addressed.

  12. High performance relaxor-based ferroelectric single crystals for ultrasonic transducer applications.

    Science.gov (United States)

    Chen, Yan; Lam, Kwok-Ho; Zhou, Dan; Yue, Qingwen; Yu, Yanxiong; Wu, Jinchuan; Qiu, Weibao; Sun, Lei; Zhang, Chao; Luo, Haosu; Chan, Helen L W; Dai, Jiyan

    2014-01-01

    Relaxor-based ferroelectric single crystals Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) have drawn much attention in the ferroelectric field because of their excellent piezoelectric properties and high electromechanical coupling coefficients (d33~2000 pC/N, kt~60%) near the morphotropic phase boundary (MPB). Ternary Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT) single crystals also possess outstanding performance comparable with PMN-PT single crystals, but have higher phase transition temperatures (rhombohedral to tetragonal Trt, and tetragonal to cubic Tc) and larger coercive field Ec. Therefore, these relaxor-based single crystals have been extensively employed for ultrasonic transducer applications. In this paper, an overview of our work and perspectives on using PMN-PT and PIN-PMN-PT single crystals for ultrasonic transducer applications is presented. Various types of single-element ultrasonic transducers, including endoscopic transducers, intravascular transducers, high-frequency and high-temperature transducers fabricated using the PMN-PT and PIN-PMN-PT crystals and their 2-2 and 1-3 composites are reported. Besides, the fabrication and characterization of the array transducers, such as phased array, cylindrical shaped linear array, high-temperature linear array, radial endoscopic array, and annular array, are also addressed. PMID:25076222

  13. Preparation of Tunable Photonic Crystal Based on Cholesteric Liquid Crystal%基于胆甾相液晶的可调制光子晶体

    Institute of Scientific and Technical Information of China (English)

    韩国志; 朱沈; 吴生蓉; 庞峰飞

    2012-01-01

    将胆甾相液晶填充进胶体晶体内部空隙,通过胆甾相液晶与胶体晶体的耦合,构建了一种新型可调制液晶光子晶体.填充于胶体晶体内部的胆甾相液晶织构呈现典型的手性近晶相(S)特征.由于胆甾相液晶具有特定的选择性反射,当胶体晶体的带隙处于胆甾相液晶的反射波长范围之内,则随着温度的改变,胶体晶体的带隙与胆甾相液晶的带隙同时发生蓝移.在一定温度条件下,胆甾相液晶的带隙将与胶体晶体的带隙发生耦合,实现了光子晶体带隙在单峰与双峰之间的可逆切换.%Via introducing cholesteric liquid crystal into voids of colloidal crystal,a novel tunable photonic colloidal crystal based on coupling of cholesteric liquid crystal(CLC) and colloidal crystal(CC) was prepared.Cholesteric liquid crystal used in this paper was prepared by combining nematic liquid crystal 5CB and the chiral dopant COC(cholesteryl oleyl carbonate),its selective reflection wavelength can be controlled by changing proportion of the mixture,and with temperature rising,blue shift of the selective reflection peak occurred.Firstly,SiO2 colloidal crystal was obtained by deposition method,then cholesteric liquid crystals was filled in voids of colloidal crystal by capillary force with temperature above the clearing point.Under polarized light microscope,the cholesteric liquid crystals in voids of colloidal crystal exhibited typical texture of chiral smectic phase in certain temperature region.Since cholesteric liquid crystal has particular selective reflection,if band gap of colloidal crystal locates in the reflection wavelength region of cholesteric liquid crystal,homodromous shift of band gap of cholesteric liquid crystal and colloidal crystal originating from changing of refraction index of cholesteric liquid crystal in voids occurred at the same time with temperature changed.But shift rate of band gap of cholesteric liquid crystal was

  14. Single-crystal tungsten-based alloys with molybdenum and rhenium

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Single crystals of ternary W-based alloys with 2 % Re and less than 7 % Mo have been grown for the first time at the Baikov Institute of Metallurgy and Materials Science RAS. Plasma arc melting allowed us to effectively purify the single crystals from a number of impurities. According to mass spectrometric analysis for 70 elements, the total content of impurities does not exceed 0. 063%. It was found that, as the Mo content increases, the size of first-kind subgrains decreases and their mutual misorientation increases. In the W-based alloy with 2.3 % Re and 6.7% Mo, no first-kind subgrains are observed,whereas second-kind subgrains are elongated along the growth direction. In this case, their total misorientation is well below that in the other low-alloy single crystals.Single-crystal of binary tungsten-based alloys with rhenium were prepared by electron-beam zone melting (1% Re, mass fraction) and plasma arc melting (2%Re, 10%Re, 25%Re (mass fraction)). It was found that the low-alloyed (1%-2 % Rh (mass fraction)) W-based alloys are characterized by a rather perfect single-crystal structure and misorientations of first- and second-kind subgrains of 20-50' and 10-40', respectively. Sections with the coarse-grained structure are observed in ingots of the alloy with 10%and 25% (mass fraction) Rh; in the alloy with 25% Rh, such structure is observed immediately from the seed.A device for measuring the liquidus and solidus temperatures of refractory metallic alloys has been designed. The liquidus temperatures of ternary single crystals (W-Mo-Re) have been measured.The studied single crystals, owing to their purity and high stability of the structure and properties,are widely used in electronics, electrical engineering, and analytical devices for various purposes.

  15. Perturbative modeling of Bragg-grating-based biosensors in photonic-crystal fibers

    DEFF Research Database (Denmark)

    Burani, Nicola; Lægsgaard, Jesper

    2005-01-01

    We present a modeling study carried out to support the design of a novel, to our knowledge, kind of photonic-crystal fiber (PCF)-based sensor. This device, based on a PCF Bragg grating, detects the presence of selected single-stranded DNA molecules, hybridized to a biofilm in the air holes of the...

  16. Investigation of frequency-selective devices based on a microstrip 2D photonic crystal

    Science.gov (United States)

    Belyaev, B. A.; Khodenkov, S. A.; Shabanov, V. F.

    2016-04-01

    The frequency-selective properties of structures based on a 2D microstrip photonic crystal have been investigated theoretically and experimentally. It is shown that various microwave devices, including diplexers, bandpass filters, and double bandpass filters, can be designed based on these structures.

  17. High-molecular-weight polymers for protein crystallization: poly-γ-glutamic acid-based precipitants

    International Nuclear Information System (INIS)

    High-molecular-weight poly-γ-glutamic acid-based polymers have been synthesized, tested and adopted for protein crystallization. Protein crystallization has been revolutionized by the introduction of high-throughput technologies, which have led to a speeding up of the process while simultaneously reducing the amount of protein sample necessary. Nonetheless, the chemistry dimension of protein crystallization has remained relatively undeveloped. Most crystallization screens are based on the same set of precipitants. To address this shortcoming, the development of new protein precipitants based on poly-γ-glutamic acid (PGA) polymers with different molecular-weight ranges is reported here: PGA-LM (low molecular weight) of ∼400 kDa and PGA-HM (high molecular weight) of >1000 kDa. It is also demonstrated that protein precipitants can be expanded further to polymers with much higher molecular weight than those that are currently in use. Furthermore, the modification of PGA-like polymers by covalent attachments of glucosamine substantially improved their solubility without affecting their crystallization properties. Some preliminary PGA-based screens are presented here

  18. Recrystallization of Single Crystal Nickel-Based Superalloy

    Institute of Scientific and Technical Information of China (English)

    ZHANG Bing; TAO Chun-hu; LU Xin; LIU Chang-kui; HU Chun-yan; BAI Ming-yuan

    2009-01-01

    A series of experiments of investigating the recrystallization of single crystal DD3 superalloy were carried out. The threshold temperature for recrystallization and the effect of annealing temperature on recrystaUization were studied. The results show that the threshold temperature for recrystallization of the shot-peened DD3 samples is be-tween 1 000 ℃ and 1 050℃ under the condition of annealing for 2 h, and the recrystallization depth increases with the rise of the annealing temperature. Below 1 150 ℃, the recrystallization depth increases slowly with the tempera-ture climbing, while above 1 150 ℃, the recrystallization depth increases quickly with the rise of the temperature. The solution of the γ' phase is a critical factor of the recrystallization behavior of DD3 superalloy. In addition, the ki-netics and microstructural evolution of recrystallization at 1 200 ℃ were also studied. It is found that the recrystalli-zation progresses rapidly at 1 200℃ through the growth of fully developed recrystallized grains, and the recrystalli-zation process on the shot-peened surface is similar to that of wrought materials, including nucleation of reerystalliza-tion, growth of new grains into the matrix, and growth of new grains by swallowing up each other.

  19. Kinetics of crystallization of a Fe-based multicomponent amorphous alloy

    Indian Academy of Sciences (India)

    Arun Pratap; T Lilly Shanker Rao; Kinnary Patel; Mukesh Chawda

    2009-10-01

    The Fe-based multicomponent amorphous alloys (also referred to as metallic glasses) are known to exhibit soft magnetic properties and, it makes them important for many technological applications. However, metallic glasses are in a thermodynamically metastable state and in case of high temperature operating conditions, the thermally activated crystallization would be detrimental to their magnetic properties. The study of crystallization kinetics of metallic glasses gives useful insight about its thermal stability. In the present work, crystallization study of Fe67Co18B14Si1 (2605CO) metallic glass has been carried out using differential scanning calorimetry (DSC) technique. Mössbauer study has also been undertaken to know the phases formed during the crystallization process. The alloy shows two-stage crystallization. The activation energy has been derived using the Kissinger method. It is found to be equal to 220 kJ/mol and 349 kJ/mol for the first and second crystallization peaks, respectively. The Mössbauer study indicates the formation of -(Fe, Co) and (Fe, Co)3B phases in the alloy.

  20. PREDICTION OF EARING IN TEXTURED ALUMINIUM SHEETS BASED ON CRYSTAL PLASTICITY

    Institute of Scientific and Technical Information of China (English)

    Chen Yiping; Dong Xianghuai; Xie Chunlei; E. Nakamachi; Li Zhigang

    2001-01-01

    The phenomenon of earing is investigated in the present study based on the theory of crystal plasticity with the dynamic explicit finite element program developed. Firstly texture analysis is carried out of rolled aluminium alloy A15052 by means of X-ray technique. Then from the texture coefficients an analytical expression for the orientation distribution function (ODF) is derived making use of the computer algebraic language Mathematica4.0, which makes it easier to discretize the ODF into a series of Eulerian angles representing the distribution of lattices and further the preferred orientation (texture) of crystals of the original sheets. For the polycrystal model, the material is described using crystal plasticity where each material point in the sheet is assumed to be a polycrystalline aggregate of a very large number of face-centered cubic (FCC)grains with each grain modelled as an FCC crystal with 12 distinct slip systems. The modified Taylor theory of crystal plasticity is used and only the initial texture is taken into consideration during large plastic deformation. Numerical simulation of earing has been performed for an aluminium sheet with texture and one with crystals exhibiting random distribution to demonstrate the effect of texture of materials on their plastic anisotropy and formability.

  1. Electrically controlled spatial-polarization switch based on patterned photoalignment of nematic liquid crystals.

    Science.gov (United States)

    Melnikova, Elena A; Tolstik, Alexei L; Rushnova, Irina I; Kabanova, Olga S; Muravsky, Alexander A

    2016-08-10

    A switching scheme for two orthogonal modes of laser radiation that is based on the total internal reflection effect realized at the interface of two liquid crystal regions with orthogonal director orientations is proposed. To create the photorefractive interface within the bulk of a liquid crystal, an original technique based on self-alignment of azo dye photoalignment and absorbing electrode patterns has been developed. Spatial separation of the orthogonally polarized light beams and their switching (when the positions of reflected and transmitted light beams are switched) due to the voltage applied has been experimentally realized. PMID:27534500

  2. Add-drop filter based on dual photonic crystal nanobeam cavities in push-pull mode

    CERN Document Server

    Poulton, Christopher V; Wade, Mark T; Popovic, Milos A

    2015-01-01

    We demonstrate an add-drop filter based on a dual photonic crystal nanobeam cavity system that emulates the operation of a traveling-wave resonator and drops light on resonance to a single output port. Realized on an advanced SOI CMOS (IBM 45nm SOI) chip without any foundry process modifications, the device shows 16dB extinction in through port and 1dB loss in drop port with a 3dB bandwidth of 64GHz. To the best of our knowledge, this is the first implementation of a four-port add-drop filter based on photonic crystal nanobeam cavities.

  3. Tunable All-in-Fiber Waveplates Based on Negative Dielectric Liquid Crystal Photonic Bandgap Fibers

    DEFF Research Database (Denmark)

    Wei, Lei; Eskildsen, Lars; Weirich, Johannes;

    2008-01-01

    Tunable all-in-fiber waveplates based on negative dielectric liquid crystal photonic bandgap fibers are presented. The birefringence can be tuned electrically and thermally to work as a quarter-wave or a half-wave plate in the range 1520 nm-1580 nm.......Tunable all-in-fiber waveplates based on negative dielectric liquid crystal photonic bandgap fibers are presented. The birefringence can be tuned electrically and thermally to work as a quarter-wave or a half-wave plate in the range 1520 nm-1580 nm....

  4. Coherent anti-Stokes Raman scattering microscopy with a photonic crystal fiber based light source

    DEFF Research Database (Denmark)

    Paulsen, H.N.; Hilligsøe, Karen Marie; Thøgersen, J.;

    2003-01-01

    A coherent anti-Stokes Raman scattering microscope based on a Ti:sapphire femtosecond oscillator and a photonic crystal fiber is demonstrated. The nonlinear response of the fiber is used to generate the additional wavelength needed in the Raman process. The applicability of the setup is demonstra......A coherent anti-Stokes Raman scattering microscope based on a Ti:sapphire femtosecond oscillator and a photonic crystal fiber is demonstrated. The nonlinear response of the fiber is used to generate the additional wavelength needed in the Raman process. The applicability of the setup...

  5. Development of crystals based in cesium iodide for application as radiation detectors

    International Nuclear Information System (INIS)

    Inorganic scintillators with fast luminescence decay time, high density and high light output have been the object of studies for application in nuclear physics, high energy physics, nuclear tomography and other fields of science and engineering. Scintillation crystals based on cesium iodide (CsI) are matters with relatively low higroscopy, high atomic number, easy handling and low cost, characteristics that favor their use as radiation detectors. In this work, the growth of pure CsI crystals, CsI:Br and CsI:Pb, using the Bridgman technique, is described. The concentration of the bromine doping element (Br) was studied in the range of 1,5x10-1 M to 10-2 M and the lead (Pb) in the range of 10-2 M to 5x10-4 M. To evaluate the scintillators developed, systematic measurements were carried out for luminescence emission and luminescence decay time for gamma radiation, optical transmittance assays, Vickers micro-hardness assays, determination of the doping elements distribution along the grown crystals and analysis of crystals response to the gamma radiation in the energy range of 350 keV to 1330 keV and alpha particles from a 241Am source, with energy of 5.54 MeV. It was obtained 13 ns to 19 ns for luminescence decay time for CsI:Br and CsI:Pb crystals. These results were very promising. The results obtained for micro-hardness showed a significant increase in function of the doping elements concentration, when compared to the pure CsI crystal, increasing consequently the mechanical resistance of the grown crystals. The validity of using these crystals as radiation sensors may be seen from the results of their response to gamma radiation and alpha particles. (author)

  6. Two-dimensional photonic-crystal-based Fabry-Perot etalon.

    Science.gov (United States)

    Ho, Chong Pei; Pitchappa, Prakash; Kropelnicki, Piotr; Wang, Jian; Cai, Hong; Gu, Yuandong; Lee, Chengkuo

    2015-06-15

    We demonstrate the design, fabrication, and characterization of a polycrystalline-silicon-based photonic crystal Fabry-Perot etalon, which is aimed to work in the mid-infrared wavelengths. The highly reflective mirrors required in a Fabry-Perot etalon are realized by freestanding polycrystalline-silicon-based photonic crystal membranes with etched circular air holes. A peak reflection of 96.4% is observed at 3.60 μm. We propose a monolithic CMOS-compatible fabrication process to configure two such photonic crystal mirrors to be in parallel to form a Fabry-Perot etalon; a filtered transmission centered at 3.51 μm is observed. The quality factor measured is around 300, which is significantly higher than in existing works. This creates the possibility of using such devices for high-resolution applications such as gas sensing and hyperspectral imaging.

  7. Experimental and numerical investigations of Si-based photonic crystals with ordered Ge quantum dots emitters

    International Nuclear Information System (INIS)

    In recent years quasi-two-dimensional (2D) photonic crystals, also known as photonic crystal slabs, have been the subject of extensive research. The present work is based on photonic crystals where a hexagonal 2D lattice of air holes is etched through a silicon-on-insulator (SOI) slab. Light is guided in the horizontal plane using photonic band-gap properties, and index guiding provides the optical confinement in the third dimension. This work discusses photonic crystal slabs with Ge quantum dots (QDs) as internal sources. Ge quantum dots have luminescence around 1500nm, which is well suited for optical fiber communication in a way that is fully compatible with standard silicon technology. QD emission can be controlled by epitaxial growth on a pre-patterned SOI substrate. In this way the position of the QDs is controlled, as well as their homogeneity and spectral emission range. During this thesis, photonic crystal fabrication techniques together with techniques for the alignment of the photonic crystal holes with the QDs positions were developed. The employed techniques involve electron beam lithography (EBL) and inductively-coupled-plasma reactive ion etching (ICP-RIE). Perfect ordering of the QDs position was achieved by employing these techniques for pit patterning and the subsequent growth of Ge dots using molecular beam epitaxy (MBE). A second EBL step was then used for photonic crystal writing, which needed to be aligned with respect to the pit pattern with a precision of about ± 30nm. Micro-photoluminescence spectroscopy was used for the optical characterization of the photonic crystal. The emission from ordered quantum dots in different symmetry positions within a unit cell of photonic crystal was theoretically and experimentally investigated and compared with randomly distributed ones. Besides, different geometrical parameters of photonic crystals were studied. The theoretical investigations were mainly based on the rigorous coupled wave analysis (RCWA

  8. Optical Properties and Wave Propagation in Semiconductor-Based Two-Dimensional Photonic Crystals

    International Nuclear Information System (INIS)

    This work is a theoretical investigation on the physical properties of semiconductor-based two-dimensional photonic crystals, in particular for what concerns systems embedded in planar dielectric waveguides (GaAs/AlGaAs, GaInAsP/InP heterostructures, and self-standing membranes) or based on macro-porous silicon. The photonic-band structure of photonic crystals and photonic-crystal slabs is numerically computed and the associated light-line problem is discussed, which points to the issue of intrinsic out-of-lane diffraction losses for the photonic bands lying above the light line. The photonic states are then classified by the group theory formalism: each mode is related to an irreducible representation of the corresponding small point group. The optical properties are investigated by means of the scattering matrix method, which numerically implements a variable-angle-reflectance experiment; comparison with experiments is also provided. The analysis of surface reflectance proves the existence of selection rules for coupling an external wave to a certain photonic mode. Such rules can be directly derived from symmetry considerations. Lastly, the control of wave propagation in weak-index contrast photonic-crystal slabs is tackled in view of designing building blocks for photonic integrated circuits. The proposed designs are found to comply with the major requirements of low-loss propagation, high and single-mode transmission. These notions are then collected to model a photonic-crystal combiner for an integrated multi-wavelength-source laser

  9. Optical Properties and Wave Propagation in Semiconductor-Based Two-Dimensional Photonic Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Mario Agio

    2002-12-31

    This work is a theoretical investigation on the physical properties of semiconductor-based two-dimensional photonic crystals, in particular for what concerns systems embedded in planar dielectric waveguides (GaAs/AlGaAs, GaInAsP/InP heterostructures, and self-standing membranes) or based on macro-porous silicon. The photonic-band structure of photonic crystals and photonic-crystal slabs is numerically computed and the associated light-line problem is discussed, which points to the issue of intrinsic out-of-lane diffraction losses for the photonic bands lying above the light line. The photonic states are then classified by the group theory formalism: each mode is related to an irreducible representation of the corresponding small point group. The optical properties are investigated by means of the scattering matrix method, which numerically implements a variable-angle-reflectance experiment; comparison with experiments is also provided. The analysis of surface reflectance proves the existence of selection rules for coupling an external wave to a certain photonic mode. Such rules can be directly derived from symmetry considerations. Lastly, the control of wave propagation in weak-index contrast photonic-crystal slabs is tackled in view of designing building blocks for photonic integrated circuits. The proposed designs are found to comply with the major requirements of low-loss propagation, high and single-mode transmission. These notions are then collected to model a photonic-crystal combiner for an integrated multi-wavelength-source laser.

  10. A novel laser-based method for controlled crystallization in dental prosthesis materials

    Science.gov (United States)

    Cam, Peter; Neuenschwander, Beat; Schwaller, Patrick; Köhli, Benjamin; Lüscher, Beat; Senn, Florian; Kounga, Alain; Appert, Christoph

    2015-02-01

    Glass-ceramic materials are increasingly becoming the material of choice in the field of dental prosthetics, as they can feature both high strength and very good aesthetics. It is believed that their color, microstructure and mechanical properties can be tuned such as to achieve an optimal lifelike performance. In order to reach that ultimate perfection a controlled arrangement of amorphous and crystalline phases in the material is required. A phase transformation from amorphous to crystalline is achieved by a heat treatment at defined temperature levels. The traditional approach is to perform the heat treatment in a furnace. This, however, only allows a homogeneous degree of crystallization over the whole volume of the parent glass material. Here a novel approach using a local heat treatment by laser irradiation is presented. To investigate the potential of this approach the crystallization process of SiO2-Li2O-Al2O3-based glass has been studied with laser systems (pulsed and continuous wave) operating at different wavelengths. Our results show the feasibility of gradual and partial crystallization of the base material using continuous laser irradiation. A dental prosthesis machined from an amorphous glassy state can be effectively treated with laser irradiation and crystallized within a confined region of a few millimeters starting from the body surface. Very good aesthetics have been achieved. Preliminary investigation with pulsed nanosecond lasers of a few hundreds nanoseconds pulse width has enabled more refinement of crystallization and possibility to place start of phase change within the material bulk.

  11. Adaptive interferometry based on dynamic reflective holograms in cubic photorefractive crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kolegov, A A; Shandarov, S M; Simonova, G V; Kabanova, L A; Burimov, Nikolai I; Shmakov, S S; Bykov, V I; Kargin, Yu F

    2011-09-30

    The characteristics of a holographic interferometer, which is based on the interaction of counterpropagating light waves on reflective holograms in cubic photorefractive sillenite crystals of the (100) cut and designed for measuring surface vibration spectra from specularly reflecting objects, have been theoretically analysed and experimentally studied. The experiments showed that an interferometer of this type, based on an Bi{sub 12}TiO{sub 20} : Fe,Cu crystal, makes it possible to measure vibrations with an amplitude of 5 pm. An analysis performed with allowance for the shot and thermal noise of the photodetector showed that vibrations with an amplitude below 1 pm can be measured. A model is proposed to describe the experimentally found strong temperature dependence of the light interaction on reflection holograms in a Bi{sub 12}TiO{sub 20} : Ca crystal. This model takes into account the influence of temperature on the photoinduced charge redistribution over deep donor and shallow trap centres, as well as the drift of the interference pattern in the crystal due to the thermooptical effect and linear expansion of the crystal.

  12. Liquid crystal bio-based epoxy coating with enhanced performance

    Directory of Open Access Journals (Sweden)

    Rasha A. El-Ghazawy,

    2014-11-01

    Full Text Available Tetrafunctional rosin based epoxy was synthesized and cured with either rosin based hardener or conventional phenylene diamine to study the feasibility of producing high performance thermosetting polymer from renewable resource. The chemical structure of the prepared epoxy was confirmed by elemental analysis, FTIR, 1HNMR, UV, total acid number and epoxy equivalent weight. Dynamic mechanical (DMA and thermogravimetric (TGA analyses results indicate that fully biobased epoxy system possesses high glass transition temperature (Tg, high modulus (G` and improved thermal stability.

  13. Novel Synthesis of Ferrocenyl Schiff Bases and Crystal Structure

    Institute of Scientific and Technical Information of China (English)

    ZHANG,Hui-Qing; ZHOU,Zhi-Ming; YU,Cong-Xuan

    2004-01-01

    @@ Ferrocenylimines have attracted additional interest due to their versatile utilities. They have been widely used as plant growth regulator, bactericide, fuel dope and new anticarcinogen.[1] And a large amount of ferrocenyl shiff bases were prepared in the past. However, study on ferrocenylimines as directing ortho metalation group (DMG) in the (-)-sparteine meditated synthesis of planar chiral ferrocene has not been reported. Herein, we synthesized a series of ferrocenyl schiff bases for this study.

  14. Finite Element Analysis of a Copper Single Crystal Shape Memory Alloy-Based Endodontic Instruments

    Science.gov (United States)

    Vincent, Marin; Thiebaud, Frédéric; Bel Haj Khalifa, Saifeddine; Engels-Deutsch, Marc; Ben Zineb, Tarak

    2015-10-01

    The aim of the present paper is the development of endodontic Cu-based single crystal Shape Memory Alloy (SMA) instruments in order to eliminate the antimicrobial and mechanical deficiencies observed with the conventional Nickel-Titane (NiTi) SMA files. A thermomechanical constitutive law, already developed and implemented in a finite element code by our research group, is adopted for the simulation of the single crystal SMA behavior. The corresponding material parameters were identified starting from experimental results for a tensile test at room temperature. A computer-aided design geometry has been achieved and considered for a finite element structural analysis of the endodontic Cu-based single crystal SMA files. They are meshed with tetrahedral continuum elements to improve the computation time and the accuracy of results. The geometric parameters tested in this study are the length of the active blade, the rod length, the pitch, the taper, the tip diameter, and the rod diameter. For each set of adopted parameters, a finite element model is built and tested in a combined bending-torsion loading in accordance with ISO 3630-1 norm. The numerical analysis based on finite element procedure allowed purposing an optimal geometry suitable for Cu-based single crystal SMA endodontic files. The same analysis was carried out for the classical NiTi SMA files and a comparison was made between the two kinds of files. It showed that Cu-based single crystal SMA files are less stiff than the NiTi files. The Cu-based endodontic files could be used to improve the root canal treatments. However, the finite element analysis brought out the need for further investigation based on experiments.

  15. Mechanisms of High Temperature/Low Stress Creep of Ni-Based Superalloy Single Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Michael J. Mills

    2009-03-05

    Cast nickel-based superalloys are used for blades in land-based, energy conversion and powerplant applications, as well as in aircraft gas turbines operating at temperatures up to 1100 C, where creep is one of the life-limiting factors. Creep of superalloy single crystals has been extensively studied over the last several decades. Surprisingly, only recently has work focused specifically on the dislocation mechanisms that govern high temperature and low stress creep. Nevertheless, the perpetual goal of better engine efficiency demands that the creep mechanisms operative in this regime be fully understood in order to develop alloys and microstructures with improved high temperature capability. At present, the micro-mechanisms controlling creep before and after rafting (the microstructure evolution typical of high temperature creep) has occurred have yet to be identified and modeled, particularly for [001] oriented single crystals. This crystal orientation is most interesting technologically since it exhibits the highest creep strength. The major goal of the program entitled ''Mechanisms of High Temperature/Low Stress Creep of Ni-Based Superalloy Single Crystals'' (DOE Grant DE-FG02-04ER46137) has been to elucidate these creep mechanisms in cast nickel-based superalloys. We have utilized a combination of detailed microstructure and dislocation substructure analysis combined with the development of a novel phase-field model for microstructure evolution.

  16. Synthesis and Crystal Structures of Schiff Bases Bearing Ferrocenylphenyl Groups

    Institute of Scientific and Technical Information of China (English)

    Yan XU; Yong FU; Mao Ping SONG; Yang Jie WU

    2005-01-01

    The Schiff bases bearing ferrocenylphenyl and diferrocenylphenyl groups were synthesized by the reactions of m-ferrocenylaniline with salicylaldehyde or 1, 4-bis (2'-formylphenyl)-1, 4-dioxabutane. The title compounds were characterized by elemental analysis, IR, 1H NMR and X-ray structural determination.

  17. Polarization Beam Splitter Based on Self-Collimation of a Hybrid Photonic Crystal

    Directory of Open Access Journals (Sweden)

    F. Bagci

    2014-12-01

    Full Text Available A photonic crystal polarization beam splitter based on photonic band gap and self-collimation effects is designed for optical communication wavelengths. The photonic crystal structure consists of a polarization-insensitive self-collimation region and a splitting region. TM- and TE-polarized waves propagate without diffraction in the self-collimation region, whereas they split by 90 degrees in the splitting region. Efficiency of more than 75% for TM- and TE-polarized light is obtained for a polarization beam splitter size of only 17 μm x 17 μm in a wavelength interval of 60 nm including 1.55 μm.

  18. Polarization splitter based on dual core liquid crystal-filled holey fiber

    Science.gov (United States)

    Wang, Er-Lei; Jiang, Hai-Ming; Xie, Kang; Chen, Chun; Hu, Zhi-Jia

    2016-09-01

    Through filling the liquid crystal into the air holes of a dual-core holey fiber with a simple structure, the transmission mechanism of the fiber is changed from total internal reflection to photonic bandgap (PBG), and a polarization splitter based on the liquid crystal-filled dual-core PBG holey fiber is investigated. The results demonstrate that, by setting appropriate geometrical parameters, the polarization splitter possesses a short length of 890.5 μm, and its wide bandwidth of ˜150 nm almost covers all the S, C, and L communication bands. Besides, it has an excellent electro-interference-resistance property and certain sensitivity to temperature.

  19. Electrically tunable Fabry-Péerot resonator based on microstructured Si containing liquid crystal

    KAUST Repository

    Tolmachev, Vladimir A.

    2012-01-01

    We have built Fabry-Perot resonators based on microstructured silicon and a liquid crystal. The devices exhibit tuning of the resonance peaks over a wide range, with relative spectral shifts of up to Delta lambda/lambda = 10%. In order to achieve this substantial spectral shift, cavity peaks of high order were used. Under applied voltages of up to 15 V, a variation in the refractive index of the nematic liquid crystal E7 from Delta n(LC) = 0.12 to Delta n(LC) = 0.17 was observed. These results may have practical applications in the near-, mid and far-infrared range.

  20. The optimum scheme of a static Fourier-transform spectrometer based on birefringent crystal

    Institute of Scientific and Technical Information of China (English)

    Dongqing Zhang(张冬青); Fuquan Wu(吴福全); Shuhai Fan(范树海)

    2003-01-01

    An optimum design of static Fourier-transform spectrometer based on Savert prisms is presented in this paper. A new method of increasing path difference and resolution of spectrometer is given. When the angle between the crystal optical axis of the first Savert prism and the incident interface is 58° and the angle between the crystal optical axis of the second Savert prism and the incident interface is 28°, the maximum path difference will be 0.63 mm, the maximum resolution will be 15.8 cm-1, and the whole field-of-view will reach 6°.

  1. Tunable pretilt angles based on nanoparticles-doped planar liquid-crystal cells.

    Science.gov (United States)

    Jeng, Shie-Chang; Hwang, Shug-June; Yang, Chen-Yu

    2009-02-15

    The nanoparticles-induced vertical alignment technique was applied to generate variable liquid-crystal pretilt angles based on doping different concentrations of polyhedral oligomeric silsesquioxane (POSS) nanoparticles in the planar-aligned liquid crystal cells. Competition between the homogeneously aligned polyimide layer and POSS-induced spontaneous vertical alignment domain generated the variable pretilt angle. Experimental results demonstrated that the pretilt angle theta(p) is a function of the doped POSS concentration and can be controlled continuously over the range of 0 degrees

  2. SNR improvement based on non-collinear OPCPA with angular spectral dispersion in BBO crystal

    Science.gov (United States)

    Ye, Rong; Zhang, Bin; Sun, Nian-chun

    2014-07-01

    The characteristics of the signal-to-noise ratio (SNR) improvement based on non-collinear optical parametric chirped pulse amplification (OPCPA) with angular spectral dispersion (ASD) was revealed and investigated. The angular dispersion formula was derived theoretically and the effects of crystal length, pump peak intensity, noise characteristics and angular dispersion on the SNR improvement and conversion efficiency were discussed. Furthermore, by optimizing the critical parameters, 35% conversion efficiency and more than 3 orders of magnitude of SNR improvement were achieved for the chirped signal pulse with a central wavelength of 800 nm, pumped by 532 nm in presented amplification scheme with BBO crystal.

  3. Hybrid crystals of cuprates and iron-based superconductors

    Institute of Scientific and Technical Information of China (English)

    代霞; 勒聪聪; 吴贤新; 胡江平

    2016-01-01

    We propose two possible new compounds, Ba2CuO2Fe2As2 and K2CuO2Fe2Se2, which hybridize the building blocks of two high temperature superconductors, cuprates and iron-based superconductors. These compounds consist of square CuO2 layers and antifluorite-type Fe2X2 (X=As, Se) layers separated by Ba/K. The calculations of binding energies and phonon spectra indicate that they are dynamically stable, which ensures that they may be experimentally synthesized. The Fermi surfaces and electronic structures of the two compounds inherit the characteristics of both cuprates and iron-based superconductors. These compounds can be superconductors with intriguing physical properties to help to determine the pairing mechanisms of high Tc superconductivity.

  4. Knowledge-Based Optimization of Molecular Geometries Using Crystal Structures.

    Science.gov (United States)

    Cole, Jason C; Groom, Colin R; Korb, Oliver; McCabe, Patrick; Shields, Gregory P

    2016-04-25

    This paper describes a novel way to use the structural information contained in the Cambridge Structural Database (CSD) to drive geometry optimization of organic molecules. We describe how CSD structural information is transformed into objective functions for gradient-based optimization to provide good quality geometries for a large variety of organic molecules. Performance is assessed by minimizing different sets of organic molecules reporting RMSD movements for bond lengths, valence angles, torsion angles, and heavy atom positions. PMID:26977906

  5. V-shape liquid crystal-based retromodulator air to ground optical communications

    CERN Document Server

    Geday, Morten A; Carrasco-Casado, Alberto; Bennis, Noureddine; Quintana, Xabier; Hernandez, Francisco Lopez; Sanchez, Jose Manuel Oton

    2015-01-01

    This paper describes the use of a 2D liquid crystal retro-modulator as a free space, wireless, optical link. The retro-modulator is made up of a retro-reflecting cornercube onto which 2 cascaded V-shape smectics liquid crystal modulators are mounted. The communication link differs with respect to more conventional optical links in not using amplitude (nor frequency) modulation, but instead state-of-polarisation (SOP) modulation known as Polarisation Shift Keying (PolSK). PolSK has the advantage over amplitude modulation, that it is less sensitive to changes in the visibility of the atmosphere, and increases inherently the bandwidth of the link. The implementation of PolSK both in liquid crystal based and in retro-modulated communication are novelties.

  6. Theoretical Strength of Face-Centred-Cubic Single Crystal Copper Based on a Continuum Model

    Institute of Scientific and Technical Information of China (English)

    LIU Xiao-Ming; LIU Zhan-Li; YOU Xiao-Chuan; NIE Jun-Feng; ZHUANG Zhuo

    2009-01-01

    The constitutive relation of single crystal copper based on atomistic potential is implemented to capture the nonlinear inter-atomic interactions. Uniaxial loading tests of single crystal copper with inter-atomic potential finite-element model are carried out to determine the corresponding ideal strength using the modified Born stability criteria. Dependence of the ideal strength on the crystallographic orientation is studied, and tension-compression asymmetry in ideal strength is also investigated. The results suggest that asymmetry for yielding strength of nano-materials may result from anisotropic character of crystal instability. Moreover, the results also reveal that the critical resolved shear stress in the direction of slip is not an accurate criterion for the ideal strength since it could not capture the dependence on the loading conditions and hydrostatic stress components for the ideal strength.

  7. High Performance Relaxor-Based Ferroelectric Single Crystals for Ultrasonic Transducer Applications

    OpenAIRE

    Yan Chen; Kwok-Ho Lam; Dan Zhou; Qingwen Yue; Yanxiong Yu; Jinchuan Wu; Weibao Qiu; Lei Sun; Chao Zhang; Haosu Luo; Chan, Helen L. W.; Jiyan Dai

    2014-01-01

    Relaxor-based ferroelectric single crystals Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) have drawn much attention in the ferroelectric field because of their excellent piezoelectric properties and high electromechanical coupling coefficients (d 33∼2000 pC/N, kt∼60%) near the morphotropic phase boundary (MPB). Ternary Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT) single crystals also possess outstanding performance comparable with PMN-PT single crystals, but have higher phase transition temperatu...

  8. Photonic crystal fibre Brillouin laser based on Bragg grating Fabry-Perot cavity

    Institute of Scientific and Technical Information of China (English)

    Geng Dan; Yang Dong-Xiao; Shen Guo-Feng; Zhang Xian-Min

    2008-01-01

    A photonic crystal fibre Brillouin laser based on fibre Bragg grating Fabry-Perot cavity is presented. A highly nonlinear photonic crystal fibre 25 m in length is used as Brillouin gain medium and fibre Bragg grating Fabry-Perot cavity is chosen in order to enhance the laser conversion efficiency and suppress the higher-order Stokes waves. The laser reaches the threshold at input power of 35 mW, and the experimental laser conversion efficiency achieves 18% of the input power of 140 mW and does not show higher-order Stokes waves. A photonic crystal fibre BriUouin laser withshorter fibre length and lower threshold is experimentally realized.

  9. Nano-scale electronic and optoelectronic devices based on 2D crystals

    Science.gov (United States)

    Zhu, Wenjuan

    In the last few years, the research community has been rapidly growing interests in two-dimensional (2D) crystals and their applications. The properties of these 2D crystals are diverse -- ranging from semi-metal such as graphene, semiconductors such as MoS2, to insulator such as boron nitride. These 2D crystals have many unique properties as compared to their bulk counterparts due to their reduced dimensionality and symmetry. A key difference is the band structures, which lead to distinct electronic and photonic properties. The 2D nature of the material also plays an important role in defining their exceptional properties of mechanical strength, surface sensitivity, thermal conductivity, tunable band-gap and their interaction with light. These unique properties of 2D crystals open up a broad territory of applications in computing, communication, energy, and medicine. In this talk, I will present our work on understanding the electrical properties of graphene and MoS2, in particular current transport and band-gap engineering in graphene, interface between gate dielectrics and graphene, and gap states in MoS2. I will also present our work on the nano-scale electronic devices (RF and logic devices) and photonic devices (plasmonic devices and photo-detectors) based on these 2D crystals.

  10. Photosensitive structures based on CuIn5Te8 single crystals: Development and properties

    International Nuclear Information System (INIS)

    A new ternary compound is synthesized for the first time, and bulk CuIn5Te8 single crystals are grown by directed crystallization of near-stoichiometric melt. It is established from X-ray diffraction patterns of grown crystals that they exhibit the structure of imperfect chalcopyrite with parameters of the unit cell of CuIn5Te8, which were close to those known for the CuInTe2 ternary compound with the composition index n = 0. First, photosensitive structures are fabricated based on CuIn5Te8 crystals, and photosensitivity spectra are obtained for them; it is shown that it is possible to achieve broadband photosensitivity under illumination of the barrier side of these crystals. From the analysis of photosensitivity spectra, the character of band-to-band transitions and corresponding energies of these transitions in CuIn5Te8 are determined. This opens up prospects to use this new semiconductor in photoconverters of solar radiation.

  11. Hybrid Crystals of Cuprates and Iron-Based Superconductors

    OpenAIRE

    Dai, Xia; Le, Congcong; Wu, Xianxin; Hu, Jiangping

    2016-01-01

    We propose two possible new compounds, Ba$_2$CuO$_2$Fe$_2$As$_2$ and K$_2$CuO$_2$Fe$_2$Se$_2$, which hybridize the building blocks of two high temperature superconductors, cuprates and iron-based superconductors. These compounds consist of square CuO$_2$ layers and antifluorite-type Fe$_2$X$_2$ (X=As,Se) layers separated by Ba/K. The calculations of binding energies and phonon spectrums indicate that they are dynamically stable, which ensures that they may be experimentally synthesized. The F...

  12. Crystallization-driven assembly of conjugated-polymer-based nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Hayward, Ryan C. [Univ. of Massachusetts, Amherst, MA (United States). Polymer Science & Engineering

    2016-10-15

    The goal of this project has been to improve our ability to simultaneously control the organization, and therefore the opto-electronic properties, of conjugated-polymer based materials across three different length-scales: 1) the molecular scale, in the sense of controlling growth and functionalization of highly crystalline semiconducting organic materials capable of efficient charge transport, 2) the nanoscale, in terms of positioning n- and p-type materials with domain sizes comparable to exciton diffusion lengths (~ 10 nm) to facilitate charge separation, and 3) the colloidal scale, such that well-defined crystalline nanoscale building blocks can be hierarchically organized into device layers. As described in more detail below, the project was successful in generating powerful new approaches to, and improved fundamental understanding of, processing and self-assembly of organic and hybrid semiconducting materials across all three length-scales. Although the goals of the project were formulated with primarily photovoltaic architectures in mind, the outcomes of the project have significant implications for a variety of conjugated-polymer-based devices including field-effect-transistors for sensors and logic devices, as well as potentially thermoelectrics and battery electrode materials. The project has resulted in 10 peer-reviewed publications to date [1-10], with several additional manuscripts currently in preparation.

  13. A photonic crystal L-shaped bend based on ring resonators

    Institute of Scientific and Technical Information of China (English)

    M. Djavid; F. Monifi; A. Ghaffari; M. S. Abrishamian

    2008-01-01

    @@ We propose a new type of two-dimensional (2D) photonic crystal L-shaped bent waveguides based on ring resonators with an acceptable bandwidth. The proposed structure mechanism is based on coupling between a waveguide and a ring resonator. This structure is designed and verified by finite-difference time-domain (FDTD) computation. Our simulation using this method gets over 90% output.

  14. Isothermal and non-isothermal crystallization kinetics of PVA + ionic liquid [BDMIM][BF4]-based polymeric films

    Science.gov (United States)

    Saroj, A. L.; Chaurasia, S. K.; Kataria, Shalu; Singh, R. K.

    2016-06-01

    The effect of ionic liquid (IL), 1-butyl-2,3-dimethylimidazolium tetrafluoroborate [BDMIM][BF4], on crystallization behavior of poly(vinyl alcohol) (PVA) has been studied by isothermal and non-isothermal differential scanning calorimetry techniques. The PVA + IL based polymer electrolyte films have been prepared using solution casting technique. To describe the isothermal and non-isothermal crystallization kinetics, several kinetic equations have been employed on PVA + IL based films. There is strong dependence of the peak crystallization temperature (Tc), relative degree of crystallity (Xt), half-time of crystallization (t1/2), crystallization rate constants (Avrami Kt and Tobin AT), and Avrami (n) and Tobin (nT) exponents on the cooling rate and IL loading.

  15. Development of a detector setup based on BGO single crystals to measure high energy gamma spectra of neutron sources

    International Nuclear Information System (INIS)

    Radiation detectors based on Bi4Ge3O12 (BGO) single crystal scintillators have many applications, mainly in high-energy physics, and nuclear industry. The BGO possesses several advantages including high density, large effective atomic number Zeff, small radiation length, high radiation hardness, stability of chemical properties, non-hygroscopic nature and much smaller afterglow which make these crystals indispensable in many applications. These crystals are the best choices for the spectroscopy of high energies gamma rays which are usually produced from (γ, n) reactions in various neutron sources. The major applications of these crystals in high energy physics and to detect high energy gammas require large size crystals. It has been well known that the signal output from BGO crystals is strongly governed by the purity and crystal defects. To grow high quality single crystals with large size and minimum number of defects has always been a daunting task for crystal growers. In this communication, we describe the growth and characterization BGO single crystals. Fabrication of a setup based on BGO scintillator useful to measure gamma-rays from an Am-Be neutron source is discussed

  16. A computational study of dielectric photonic-crystal-based accelerator cavities

    Science.gov (United States)

    Bauer, C. A.

    Future particle accelerator cavities may use dielectric photonic crystals to reduce harmful wakefields and increase the accelerating electric field (or gradient). Reduced wakefields are predicted based on the bandgap property of some photonic crystals (i.e. frequency-selective reflection/transmission). Larger accelerating gradients are predicted based on certain dielectrics' strong resistance to electrical breakdown. Using computation, this thesis investigated a hybrid design of a 2D sapphire photonic crystal and traditional copper conducting cavity. The goals were to test the claim of reduced wakefields and, in general, judge the effectiveness of such structures as practical accelerating cavities. In the process, we discovered the following: (1) resonant cavities in truncated photonic crystals may confine radiation weakly compared to conducting cavities (depending on the level of truncation); however, confinement can be dramatically increased through optimizations that break lattice symmetry (but retain certain rotational symmetries); (2) photonic crystal cavities do not ideally reduce wakefields; using band structure calculations, we found that wakefields are increased by flat portions of the frequency dispersion (where the waves have vanishing group velocities). A complete comparison was drawn between the proposed photonic crystal cavities and the copper cavities for the Compact Linear Collider (CLIC); CLIC is one of the candidates for a future high-energy electron-positron collider that will study in greater detail the physics learned at the Large Hadron Collider. We found that the photonic crystal cavity, when compared to the CLIC cavity: (1) can lower maximum surface magnetic fields on conductors (growing evidence suggests this limits accelerating gradients by inducing electrical breakdown); (2) shows increased transverse dipole wakefields but decreased longitudinal monopole wakefields; and (3) exhibits lower accelerating efficiencies (unless a large photonic

  17. Challenges and Opportunities for New Protein Crystallization Strategies in Structure-Based Drug Design

    Science.gov (United States)

    Grey, Jessica; Thompson, David

    2010-01-01

    Structure-based drug design (SBDD) has emerged as a valuable pharmaceutical lead discovery tool, showing potential for accelerating the discovery process, while reducing developmental costs and boosting potencies of the drug that is ultimately selected. SBDD is a iterative, rational, lead compound sculpting process that involves both the synthesis of new derivatives and the evaluation of their binding to the target structure either through computational docking or elucidation of the target structure as a complex with the lead compound. This method heavily relies on the production of high-resolution (< 2Å) three-dimensional structures of the drug target, obtained through X-ray crystallographic analysis, in the presence or absence of the drug candidate. The lack of generalized methods for high quality crystal production is still a major bottleneck in the process of macromolecular crystallization. This review provides a brief introduction to SBDD and describes several macromolecular crystallization strategies, with an emphasis on advances and challenges facing researchers in the field today. Recent trends in the development of more universal macromolecular crystallization techniques, particularly nucleation-based techniques that are applicable to both soluble and integral membrane proteins, are also discussed. PMID:21116481

  18. Optoelectronic switch and continuously tunable filter based on a liquid crystal waveguide

    Science.gov (United States)

    Sirleto, Luigi; Coppola, Giuseppe; D'Agata, Antonella; Breglio, Giovanni; Cutolo, Antonello

    2001-05-01

    In this paper the possibility of using ferroelectric liquid crystals in active waveguide devices is explored through the analysis of an integrated electro-optic switch and a continuously tunable filter. The design and the analysis of tow electro-optical devices, based on a Bragg grating integrated in a glass waveguide having liquid crystal as cover, are presented. The integrated optics structure allows to change the reflectivity of the Bragg mirror by means of electro-optic effects of smectic liquid crystals. The integrated fast electro-optic switch is based on electro- optic properties of smectic C* in the Surface Stabilized liquid crystal structure and on the selective properties of integrated Bragg grating. It presents the output directly in the frequency domain, overcoming the typical problems of intensity dependent devices, without requiring external electronic circuit. Moreover the possibility to realize a novel continuously tunable integrated filter, combining the linear electro-optic effect of smectic A* and the selective property of Bragg grating, has been explored. The proposed filter is characterized by a narrow bandwidth, desired feature for WDM technique. The principal advantages of such device include fast tuning speed, wide tuning range, low power consumption and low cost.

  19. PCR-based gene synthesis to produce recombinant proteins for crystallization

    Directory of Open Access Journals (Sweden)

    Byrne-Steele Miranda L

    2008-04-01

    Full Text Available Abstract Background Gene synthesis technologies are an important tool for structural biology projects, allowing increased protein expression through codon optimization and facilitating sequence alterations. Existing methods, however, can be complex and not always reproducible, prompting researchers to use commercial suppliers rather than synthesize genes themselves. Results A PCR-based gene synthesis method, referred to as SeqTBIO, is described to efficiently assemble the coding regions of two novel hyperthermophilic proteins, PAZ (Piwi/Argonaute/Zwille domain, a siRNA-binding domain of an Argonaute protein homologue and a deletion mutant of a family A DNA polymerase (PolA. The gene synthesis procedure is based on sequential assembly such that homogeneous DNA products can be obtained after each synthesis step without extensive manipulation or purification requirements. Coupling the gene synthesis procedure to in vivo homologous recombination techniques allows efficient subcloning and site-directed mutagenesis for error correction. The recombinant proteins of PAZ and PolA were subsequently overexpressed in E. coli and used for protein crystallization. Crystals of both proteins were obtained and they were suitable for X-ray analysis. Conclusion We demonstrate, by using PAZ and PolA as examples, the feasibility of integrating the gene synthesis, error correction and subcloning techniques into a non-automated gene to crystal pipeline such that genes can be designed, synthesized and implemented for recombinant expression and protein crystallization.

  20. Fragment-Based Electronic Structure Approach for Computing Nuclear Magnetic Resonance Chemical Shifts in Molecular Crystals.

    Science.gov (United States)

    Hartman, Joshua D; Beran, Gregory J O

    2014-11-11

    First-principles chemical shielding tensor predictions play a critical role in studying molecular crystal structures using nuclear magnetic resonance. Fragment-based electronic structure methods have dramatically improved the ability to model molecular crystal structures and energetics using high-level electronic structure methods. Here, a many-body expansion fragment approach is applied to the calculation of chemical shielding tensors in molecular crystals. First, the impact of truncating the many-body expansion at different orders and the role of electrostatic embedding are examined on a series of molecular clusters extracted from molecular crystals. Second, the ability of these techniques to assign three polymorphic forms of the drug sulfanilamide to the corresponding experimental (13)C spectra is assessed. This challenging example requires discriminating among spectra whose (13)C chemical shifts differ by only a few parts per million (ppm) across the different polymorphs. Fragment-based PBE0/6-311+G(2d,p) level chemical shielding predictions correctly assign these three polymorphs and reproduce the sulfanilamide experimental (13)C chemical shifts with 1 ppm accuracy. The results demonstrate that fragment approaches are competitive with the widely used gauge-invariant projector augmented wave (GIPAW) periodic density functional theory calculations. PMID:26584373

  1. All-optical digital 4 × 2 encoder based on 2D photonic crystal ring resonators

    Science.gov (United States)

    Moniem, Tamer A.

    2016-04-01

    The photonic crystals draw significant attention to build all-optical logic devices and are considered one of the solutions for the opto-electronic bottleneck via speed and size. The paper presents a novel optical 4 × 2 encoder based on 2D square lattice photonic crystals of silicon rods. The main realization of optical encoder is based on the photonic crystal ring resonator NOR gates. The proposed structure has four logic input ports, two output ports, and two bias input port. The photonic crystal structure has a square lattice of silicon rods with a refractive index of 3.39 in air. The structure has lattice constant 'a' equal to 630 nm and bandgap range from 0.32 to 044. The total size of the proposed 4 × 2 encoder is equal to 35 μm × 35 μm. The simulation results using the dimensional finite difference time domain and Plane Wave Expansion methods confirm the operation and the feasibility of the proposed optical encoder for ultrafast optical digital circuits.

  2. Characterization of a PET detector head based on continuous LYSO crystals and monolithic, 64-pixel silicon photomultiplier matrices

    International Nuclear Information System (INIS)

    The characterization of a PET detector head based on continuous LYSO crystals and silicon photomultiplier (SiPM) arrays as photodetectors has been carried out for its use in the development of a small animal PET prototype. The detector heads are composed of a continuous crystal and a SiPM matrix with 64 pixels in a common substrate, fabricated specifically for this project. Three crystals of 12 mm x 12 mm x 5 mm size with different types of painting have been tested: white, black and black on the sides but white on the back of the crystal. The best energy resolution, obtained with the white crystal, is 16% FWHM. The detector response is linear up to 1275 keV. Tests with different position determination algorithms have been carried out with the three crystals. The spatial resolution obtained with the center of gravity algorithm is around 0.9 mm FWHM for the three crystals. As expected, the use of this algorithm results in the displacement of the reconstructed position toward the center of the crystal, more pronounced in the case of the white crystal. A maximum likelihood algorithm has been tested that can reconstruct correctly the interaction position of the photons also in the case of the white crystal.

  3. Kinetics of Isothermal Melt Crystallization in CaO-SiO2-CaF2-Based Mold Fluxes

    Science.gov (United States)

    Seo, Myung-Duk; Shi, Cheng-Bin; Baek, Ji-Yeon; Cho, Jung-Wook; Kim, Seon-Hyo

    2015-10-01

    A kinetic study for isothermal melt crystallization of CaO-SiO2-CaF2-based mold fluxes with different basicity of 0.94 and 1.34 has been carried out systematically by DSC measurements. The kinetic parameters were determined by Johnson-Mehl-Avrami equation. The average Avrami exponent of cuspidine (3CaO·2SiO2·CaF2) crystallization for mold flux of lower basicity (0.94) is calculated to be 3.1, implying that the crystallization mode is instantaneous nucleation followed by 3-dimensional growth. For the mold flux of higher basicity (1.34), the average Avrami exponent of cuspidine equals to 3.4, strongly suggesting that the growth is still 3 dimensional but the nucleation should be continuous. It was found that the effective crystallization rate constant for both mold fluxes increases as the crystallization temperature decreases, showing that the crystallization rate could be governed by nucleation rate. The negative effective activation energy indicates an anti-Arrhenius behavior for crystallization of the mold fluxes studied. Therefore, it is concluded that the melt crystallization for the commercial mold fluxes will be determined by thermodynamics of nucleation which is relevant to degree of undercooling. The morphology of cuspidine crystals observed by SEM agreeds well with the isothermal crystallization kinetics results.

  4. Crystal growth limitation as a critical factor for formation of Fe-based bulk metallic glasses

    International Nuclear Information System (INIS)

    In the present work we study the formation mechanism and crystallization behavior of Fe-based bulk metallic glasses influenced by the addition of rare-earth elements. Samples are characterized by conventional X-ray diffractometry, optical microscopy, and high-resolution field-emission-gun scanning and transmission electron microscopy. In the rare-earth-containing alloys, bulk metallic glasses are formed with populations of quenched-in nuclei. Consequently, crystallization on isothermal annealing occurs without any incubation period. This behavior, not typical of bulk metallic glasses in general, implies that in the rare-earth-containing alloys glass formation is possible only because of restricted crystal growth: both on cooling from the molten and on heating from the glassy state, growth of the primary χ-Fe36Cr12Mo10 crystals is too slow to be significant on a reasonable timescale. The low growth rate is connected with large inhomogeneous strain in the growing nanoparticles, while nucleation of eutectic colonies is hampered by slow diffusion of a rare-earth alloying element

  5. Three-visible-light wave combiner based on photonic crystal waveguides.

    Science.gov (United States)

    Liu, Dingwen; Sun, Yiling; Ouyang, Zhengbiao

    2014-07-20

    We present a three-visible-light wave combiner based on two-dimensional photonic crystal waveguides whose widths are not integral multiples of the lattice period. The proposed device consists of two cascaded directional couplers. It combines three visible light waves with different wavelengths from three input ports into a single output port. As an example, a combiner for combining light waves of 635, 532, and 488 nm, which are commonly used as the three primary colors in laser display systems, is designed and demonstrated through the finite-difference time-domain method. The results show that the proposed device can perform efficient synthesis for three visible light waves with transmittance exceeding 89% for each wavelength and high ability in preventing the backward coupling of waves from different waveguides. The method for designing the combiner is useful for designing other waveguide couplers based on photonic crystals made of dispersion materials.

  6. A dinuclear cadmium(II) Schiff base thiocyanato complex: crystal structure and fluorescence.

    Science.gov (United States)

    Shit, Shyamapada; Sankolli, Ravish; Guru Row, Tayur N

    2014-01-01

    A new dinuclear cadmium(II) complex, [Cd(L)(NCS)]2 (1) has been synthesized using a potentially tetradentate Schiff base ligand HL, 2-((E)-(2-(diethylamino)ethylimino)methyl)-6-methoxyphenol, obtained by the condensation of 2-diethylaminoethylamine and o-vanillin, and characterized by different physicochemical techniques. Crystal structure of the title complex was unambiguously established by single crystal X-ray diffraction which reveals that metal centers are connected by bridging phenolato and chelating methoxy oxygen atoms of the coordinating Schiff bases and embedded in severely distorted octahedral geometries. Fluorescence properties of the ligand and its complex, studied at room temperature indicate that later may serve as strong fluorescent emitter. PMID:24664327

  7. Single-Photon Technologies Based on Quantum-Dots in Photonic Crystals

    DEFF Research Database (Denmark)

    Lehmann, Tau Bernstorff

    In this thesis, the application of semiconductor quantum-dots in photonic crystals is explored as aresource for single-photon technology.Two platforms based on photonic crystals, a cavity and a waveguide, are examined as platformssingle-photon sources. Both platforms demonstrate strong single-photon...... purity under quasi-resonantexcitation. Furthermore the waveguide based platform demonstrates indistinguishable single-photonsat timescales up to 13 ns.A setup for active demultiplexing of single-photons to a three-fold single-photon state is proposed.Using a fast electro-optical modulator, single-photons...... from a quantum-dot are routed on timescalesof the exciton lifetime. Using active demultiplexing a three-fold single-photon state is generated at anextracted rate of 2:03 ±0:49 Hz.An on-chip power divider integrated with a quantum-dot is investigated. Correlation measurementof the photon statistic...

  8. Performance in real condition of photonic crystal sensor based NO2 gas monitoring system

    Science.gov (United States)

    Rahmat, M.; Maulina, W.; Rustami, E.; Azis, M.; Budiarti, D. R.; Seminar, K. B.; Yuwono, A. S.; Alatas, H.

    2013-11-01

    In this report we discuss the performance in real condition of an optical based real-time NO2 gas monitoring system. For detecting the gas concentration in the ambient air we have developed an optical sensor based on one-dimensional photonic crystal with two defects that allows the existence of photonic pass band inside the associated photonic band gap. To measure the gas concentration, we dissolve the corresponding NO2 gas into a specific Griess Saltzman reagent solution. The change of gas concentration in the related dissolved-solution can be inspected by the photonic pass band peak variation. It is observed that the wavelength of the photonic pass band peak of the fabricated photonic crystal is nearly coincide with the wavelength of the associated solution highest absorbance. The laboratory test shows that the device works properly, whereas the field measurement test demonstrates accurate results with validation error of 1.56%.

  9. theoretical analysis of finite-height semiconductor-on-insulator based planar photonic crystal waveguides

    DEFF Research Database (Denmark)

    Søndergaard, Thomas; Arentoft, Jesper

    2002-01-01

    A planar photonic crystal waveguide based on the semiconductor-on-insulator (SOI) materials system is analyzed theoretically. Two-dimensional (2-D) calculations and comparison with dispersion relations for the media above and below the finite-height waveguide are used to obtain design guidelines....... of light for the third frequency interval is explained theoretically by investigating the vertical localization of the guided modes....

  10. Localized Mode Enhanced Coupler Based on Quasi-One-Dimensional Photonic Crystal Microstrip

    Institute of Scientific and Technical Information of China (English)

    LI Yun-Hui; JIANG Hai-Tao; HE Li; LI Hong-Qiang; ZHANG Ye-Wen; CHEN Hong

    2004-01-01

    We propose a novel localized mode enhanced (LME) coupler based on quasi-one-dimensional photonic crystal microstrips, which is promising to be applied in wavelength division multiplexed microwave communication systems. Compared to the traditional microstrip coupler, the LME structure has two advantages: high efficiency and frequency selectivity. Even in a relatively far coupling distance, this structure can still achieve a high efficiency about 50%. The frequency selectivity can be realized by simply tuning the distance between two transmission lines.

  11. Fluid Sensor Based on Transmission Dip Caused by Mini Stop-Band in Photonic Crystal Slab

    Institute of Scientific and Technical Information of China (English)

    CAO Lei; HUANG Yi-Dong; MAO Xiao-Yu; LI Fei; ZHANG Wei; PENG Jiang-De

    2008-01-01

    We propose a fluid sensor based on transmission dip caused by mini stop-band in photonic crystal slabs. Simulation results show that this novel type of sensors has large detective range (more than 1.5) and relative high sensitivity (4.3×10-5 in certain conditions). The central frequency and bandwidth of the mini stop-bands depend on the structure parameters of PC waveguides, which makes it possible to optimize the detective range and detective sensitivity.

  12. Mode decoupling in solid state ring laser based on stimulated Raman effect in polar crystals

    Institute of Scientific and Technical Information of China (English)

    Luo Zhang; Yuan Xiao-Dong; Ye Wei-Min; Zeng Chun; Ji Jia-Rong

    2011-01-01

    In this paper we study the gain saturation induced mode-coupling control in solid state ring laser devices based on the stimulated Raman effect of the polar crystals in order to realize solid state ring laser gyroscopes. We theoretically investigate the mode coupling induced by gain saturation between clockwise (CW) and counterclockwise (CCW) propagating laser modes. Because the CW and CCW running waves are pumped with counter-propagating lasers respectively, the independent coexistence can be ensured.

  13. Luminescence-induced noise in single photon sources based on BBO crystals

    Science.gov (United States)

    Machulka, Radek; Lemr, Karel; Haderka, Ondřej; Lamperti, Marco; Allevi, Alessia; Bondani, Maria

    2014-11-01

    Single-photon sources based on the process of spontaneous parametric down-conversion play a key role in various applied disciplines of quantum optics. We characterize the intrinsic luminescence of BBO crystals as a source of non-removable noise in quantum-optics experiments. By analysing its spectral and temporal properties together with its intensity, we evaluate the impact of luminescence on single-photon state preparation using spontaneous parametric down-conversion.

  14. Development of an application specific scintimammography detector based on a crystal scintillator array and a PSPMT

    CERN Document Server

    Majewski, S; Goode, A; Kross, B J; Steinbach, D; Weisenberger, A; Williams, M; Wojci, R

    1998-01-01

    We report the results of studies conducted with small field of view scintimammography camera based on a position-sensitive photomultiplier tube (5'' Hamamatsu R3292) and several pixelized crystal scintillator arrays made of YAP, CsI(Na) and NaI(Tl) scintillators. Laboratory tests and pre-clinical phantom studies were conducted to compare and optimize the performances of the prototypes with special emphasis on spatial resolution (approx 2-3mm) and sufficient energy resolution for scatter rejection.

  15. Modeling Textural Processes during Self-Assembly of Plant-Based Chiral-Nematic Liquid Crystals

    Directory of Open Access Journals (Sweden)

    Yogesh K. Murugesan

    2010-12-01

    Full Text Available Biological liquid crystalline polymers are found in cellulosic, chitin, and DNA based natural materials. Chiral nematic liquid crystalline orientational order is observed frozen-in in the solid state in plant cell walls and is known as a liquid crystal analogue characterized by a helicoidal plywood architecture. The emergence of the plywood architecture by directed chiral nematic liquid crystalline self assembly has been postulated as the mechanism that leads to optimal cellulose fibril organization. In natural systems, tissue growth and development takes place in the presence of inclusions and secondary phases leaving behind characteristic defects and textures, which provide a unique testing ground for the validity of the liquid crystal self-assembly postulate. In this work, a mathematical model, based on the Landau-de Gennes theory of liquid crystals, is used to simulate defect textures arising in the domain of self assembly, due to presence of secondary phases representing plant cells, lumens and pit canals. It is shown that the obtained defect patterns observed in some plant cell walls are those expected from a truly liquid crystalline phase. The analysis reveals the nature and magnitude of the viscoelastic material parameters that lead to observed patterns in plant-based helicoids through directed self-assembly. In addition, the results provide new guidance to develop biomimetic plywoods for structural and functional applications.

  16. DARPin-Based Crystallization Chaperones Exploit Molecular Geometry as a Screening Dimension in Protein Crystallography.

    Science.gov (United States)

    Batyuk, Alexander; Wu, Yufan; Honegger, Annemarie; Heberling, Matthew M; Plückthun, Andreas

    2016-04-24

    DARPin libraries, based on a Designed Ankyrin Repeat Protein consensus framework, are a rich source of binding partners for a wide variety of proteins. Their modular structure, stability, ease of in vitro selection and high production yields make DARPins an ideal starting point for further engineering. The X-ray structures of around 30 different DARPin complexes demonstrate their ability to facilitate crystallization of their target proteins by restricting flexibility and preventing undesired interactions of the target molecule. However, their small size (18 kDa), very hydrophilic surface and repetitive structure can limit the DARPins' ability to provide essential crystal contacts and their usefulness as a search model for addressing the crystallographic phase problem in molecular replacement. To optimize DARPins for their application as crystallization chaperones, rigid domain-domain fusions of the DARPins to larger proteins, proven to yield high-resolution crystal structures, were generated. These fusions were designed in such a way that they affect only one of the terminal capping repeats of the DARPin and do not interfere with residues involved in target binding, allowing to exchange at will the binding specificities of the DARPin in the fusion construct. As a proof of principle, we designed rigid fusions of a stabilized version of Escherichia coli TEM-1 β-lactamase to the C-terminal capping repeat of various DARPins in six different relative domain orientations. Five crystal structures representing four different fusion constructs, alone or in complex with the cognate target, show the predicted relative domain orientations and prove the validity of the concept.

  17. sl3-web bases, intermediate crystal bases and categorification

    DEFF Research Database (Denmark)

    Tubbenhauer, Daniel

    2014-01-01

    We give an explicit graded cellular basis of the sl3-web algebra K_S. In order to do this, we identify Kuperberg's basis for the sl3-web space W_S with a version of Leclerc-Toffin's intermediate crystal basis and we identify Brundan, Kleshchev and Wang's degree of tableaux with the weight of flow...

  18. Control of Process Operations and Monitoring of Product Qualities through Generic Model-based Framework in Crystallization Processes

    DEFF Research Database (Denmark)

    Abdul Samad, Noor Asma Fazli Bin

    to generate the necessary problem-system specific model, the necessary set point using the extended analytical CSD estimator and the response surface method (RSM) and a PAT system design including implementation of monitoring tools and control strategies in order to produce a desired product with its......A generic and systematic model-based framework for the design of a process monitoring and control system to achieve the desired crystal size distribution (CSD) and crystal shape for a wide range of crystallization processes has been developed. This framework combines a generic multi......-based framework is divided into three sections: a) the application of the generic multi-dimensional modelling framework are highlighted: i) the capability to develop and further extend a batch cooling crystallization model is illustrated through a paracetamol case study, supplemented by a sucrose crystallization...

  19. Rhombohedral cubic semiconductor materials on trigonal substrate with single crystal properties and devices based on such materials

    Science.gov (United States)

    Park, Yeonjoon (Inventor); Choi, Sang Hyouk (Inventor); King, Glen C. (Inventor); Elliott, James R. (Inventor)

    2012-01-01

    Growth conditions are developed, based on a temperature-dependent alignment model, to enable formation of cubic group IV, group II-V and group II-VI crystals in the [111] orientation on the basal (0001) plane of trigonal crystal substrates, controlled such that the volume percentage of primary twin crystal is reduced from about 40% to about 0.3%, compared to the majority single crystal. The control of stacking faults in this and other embodiments can yield single crystalline semiconductors based on these materials that are substantially without defects, or improved thermoelectric materials with twinned crystals for phonon scattering while maintaining electrical integrity. These methods can selectively yield a cubic-on-trigonal epitaxial semiconductor material in which the cubic layer is substantially either directly aligned, or 60 degrees-rotated from, the underlying trigonal material.

  20. The Role of Weak Interactions in the Mechano-induced Single-Crystal-to-Single-Crystal Phase Transition of 8-Hydroxyquinoline-Based Co-crystals.

    Science.gov (United States)

    Liu, Jie; Liu, Guangfeng; Liu, Yang; Zheng, Xiaoxin; Han, Quanxiang; Ye, Xin; Tao, Xutang

    2016-06-01

    Mechano-induced single-crystal-to-single-crystal (SCSC) phase transitions in crystalline materials that change their properties have received more and more attention. However, there are still too few examples to study molecular-level mechanisms in the mechano-induced SCSC phase transitions, making the systematic and in-depth understanding very difficult. We report that bis-(8-hydroxyquinolinato) palladium(II)-tetracyanoquinodimethane (PdQ2 -TCNQ) and bis-(8-hydroxyquinolinato) copper(II)-tetracyanoquinodimethane (CuQ2 -TCNQ) show very different mechano-response behaviors during the SCSC phase transition. Phase transition in CuQ2 -TCNQ can be triggered by pricking on the crystal surface, while in PdQ2 -TCNQ it can only be induced by applying pressure uniformly over the whole crystal face. The crystallography data and Hirshfeld surface analysis indicate that the weak intra-layer C-H⋅⋅⋅O, C-H⋅⋅⋅N hydrogen bonds and inter-layer stacking interactions determine the feasibility of the SCSC phase transition by mechanical stimuli. Weaker intra-layer interactions and looser inter-layer stacking make the SCSC phase transition occur much more easily in the CuQ2 -TCNQ. PMID:27124771

  1. Correlation Between Superheated Liquid Fragility And Onset Temperature Of Crystallization For Al-Based Amorphous Alloys

    Directory of Open Access Journals (Sweden)

    Guo J.

    2015-06-01

    Full Text Available Amorphous alloys or metallic glasses have attracted significant interest in the materials science and engineering communities due to their unique physical, mechanical, and chemical properties. The viscous flow of amorphous alloys exhibiting high strain rate sensitivity and homogeneous deformation is considered to be an important characteristic in thermoplastic forming processes performed within the supercooled liquid region because it allows superplastic-like deformation behavior. Here, the correlation between the superheated liquid fragility, and the onset temperature of crystallization for Al-based alloys, is investigated. The activation energy for viscous flow of the liquid is also investigated. There is a negative correlation between the parameter of superheated liquid fragility and the onset temperature of crystallization in the same Al-based alloy system. The activation energy decreases as the onset temperature of crystallization increases. This indicates that the stability of a superheated liquid can affect the thermal stability of the amorphous alloy. It also means that a liquid with a large superheated liquid fragility, when rapidly solidified, forms an amorphous alloy with a low thermal stability.

  2. Prediction of recrystallisation in single crystal nickel-based superalloys during investment casting

    Directory of Open Access Journals (Sweden)

    Panwisawas Chinnapat

    2014-01-01

    Full Text Available Production of gas turbines for jet propulsion and power generation requires the manufacture of turbine blades from single crystal nickel-based superalloys, most typically using investment casting. During the necessary subsequent solution heat treatment, the formation of recrystallised grains can occur. The introduction of grain boundaries into a single crystal component is potentially detrimental to performance, and therefore manufacturing processes and/or component geometries should be designed to prevent their occurrence. If the boundaries have very low strength, they can degrade the creep and fatigue properties. The root cause for recrystallisation is microscale plasticity caused by differential thermal contraction of metal, mould and core; when the plastic deformation is sufficiently large, recrystallisation takes place. In this work, numerical and thermo-mechanical modelling is carried out, with the aim of establishing computational methods by which recrystallisation during the heat treatment of single crystal nickel-based superalloys can be predicted and prevented prior to their occurrence. Elasto-plastic law is used to predict the plastic strain necessary for recrystallisation. The modelling result shows that recrystallisation is most likely to occur following 1.5–2.5% plastic strain applied at temperatures between 1000 ∘C and 1300 ∘C; this is validated with tensile tests at these elevated temperatures. This emphasises that high temperature deformation is more damaging than low temperature deformation.

  3. Ultracompact ring resonator microwave photonic filters based on photonic crystal waveguides.

    Science.gov (United States)

    Shen, Guansheng; Tian, Huiping; Ji, Yuefeng

    2013-02-20

    We design two microwave photonic filters (notch filter and bandpass filter) based on silicon on insulator (SOI) photonic crystal waveguides for a 60 GHz single-sideband signal radio-over-fiber (ROF) system. By perturbing the radii of the first two rows of holes adjacent to the photonic crystal waveguide, we obtained a broad negligible dispersion bandwidth and a corresponding constant low group velocity. With the slow light effect, the delay line of filters can be significantly reduced while providing the same delay time as fiber based delay lines. The simulation results show that the delay-line length of the notch filter is only about 25.9 μm, and it has a free spectral range of 130 GHz, a baseband width (BW) of 4.12 GHz, and a notch depth of 22 dB. The length of the bandpass filter is 62.4 μm, with a 19.6 dB extinction ratio and a 4.02 GHz BW, and the signal-to-noise ratio requirement of received data can be reduced by 9 dB for the 10(-7) bit-error ratio. Demonstrated microwave photonic crystal filters could be used in a future high-frequency millimeter ROF system. PMID:23434992

  4. A Rayleigh number based dendrite fragmentation criterion for detachment of solid crystals during solidification

    International Nuclear Information System (INIS)

    Movement of solid crystals in the form of dendrite fragments causes severe macro-segregation in solidified products. Dendrite fragmentation in the developing mushy zone occurs as a result of remelting (causing dissolution) and subsequent breakage of dendritic side arms from the dendritic stalks. An understanding of the mechanisms of dendrite fragmentation is essential for predicting the transport of fragmented solid crystals for possible control of macro-segregation. In this work, a Rayleigh number based fragmentation criterion is developed for detachment of dendrites from the developing mushy zone, which determines the conditions favourable for fragmentation of dendrites. The Rayleigh number, defined in this paper, measures the ratio of the driving buoyancy force for the flow in the mushy zone to the retarding frictional force associated with the permeability of the mush. The criterion developed is a function of the concentration difference, liquid fraction, permeability, growth rate of mushy layer and thermophysical properties of the material

  5. Crystal structure of a new hybrid compound based on an iodido-plumbate(II) anionic motif.

    Science.gov (United States)

    Mokhnache, Oualid; Boughzala, Habib

    2016-01-01

    Crystals of the one-dimensional organic-inorganic lead iodide-based compound catena-poly[bis-(piperazine-1,4-diium) [[tetra-iodido-plumbate(II)]-μ-iodido] iodide monohydrate], (C4N2H12)2[PbI5]I·H2O, were obtained by slow evaporation at room temperature of a solution containing lead iodide and piperazine in a 1:2 molar ratio. Inorganic lead iodide chains, organic (C4N2H12)(2+) cations, water mol-ecules of crystallization and isolated I(-) anions are connected through N-H⋯·I, N-H⋯OW and OW-H⋯I hydrogen-bond inter-actions. Zigzag chains of corner-sharing [PbI6](4-) octa-hedra with composition [PbI4/1I2/2](3-) running parallel to the a axis are present in the structure packing.

  6. TEM microstructural analysis of creep deformed CM186LC single crystal Ni-base superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Dubiel, B.; Czyrska-Filemonowicz, A. [AGH Univ. of Science and Technology, Krakow (Poland); Blackler, M. [Howmet Ltd., Exeter (United Kingdom); Barnard, P.M. [ALSTOM Power Turbo-Systems Technology Centre, Rugby (United Kingdom)

    2006-07-01

    The nickel based single crystal superalloy CM186LC was extensively investigated as a potential low cost material for industrial gas turbine vanes within the COST522 programme. The alloy exhibits inhomogeneous structure consisting of dendritic regions and eutectic colonies. In the present work attention is focused on microstructural changes observed in single crystal CM186LC following creep deformation at 750 C. Creep tests were conducted at 750 C with an applied stress of 560 or 675 MPa for up to 11440 hours. The microstructure o ruptured and terminated specimens was investigated by scanning (SEM) and transmission (TEM) electron microscopy. TEM analysis revealed the microstructural changes in the CM186LC at primary and secondary creep as well as after creep rupture. (orig.)

  7. Crystallization of a Ti-based Bulk Metallic Glass Induced by Electropulsing Treatment

    Institute of Scientific and Technical Information of China (English)

    Yong-jiang HUANG; Xiang CHENG; Hong-bo FAN; Shi-song GUAN; Zhi-liang NING; Jian-fei SUN

    2016-01-01

    The effect of electropulsing treatment (EPT)on the microstructure of a Ti-based bulk metallic glass (BMG)has been studied.The maximum current density applied during EPT can exert a crucial role on tuning the microstructure of the BMG.When the maximum current density is no more than 2 720 A/mm2 ,the samples retains amorphous nature,whereas,beyond that,crystalline phases precipitate from the glassy matrix.During EPT,the maximum temperature within the samples EPTed at the maximum current densities larger than 2 720 A/mm2 is higher than the crystallization temperature of the BMG,leading to the crystallization event.

  8. DENDRITE REFINING AND EUTECTIC TRANSFORMATION BEHAVIOR OF NICKEL-BASE SINGLE CRYSTAL (NBSC) SUPERALLOY

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    Because of the low temperature gradient and growth rate, the microstructure of the conventional single crystal superalloy made by HRS processing is coarse dendrite with well developed sidebranches and has serious segregation. With the help of the high temperature gradient directional solidification equipment (HGDS), the solidification cooling rate is greatly increased. Study on microstructure of the Ni-base single crystal superalloy solidified at much higher cooling rate shows that the dendrite arm spacing is highly refined, of which the primary dendrite arm spacing can be made to be 38μm, just as 1/10 as that by conventional HRS processing. With the increase of the cooling rate, the amount of the eutectic increases and then decreases. In the superfine columnar dendrite, the amount of γ/γ′eutectic is much fewer and its size is very small. This is useful to homogenize the microsegregation and improve the property of the material.

  9. Evaluation of optical properties for real photonic crystal fiber based on total variation in wavelet domain

    Science.gov (United States)

    Shen, Yan; Wang, Xin; Lou, Shuqin; Lian, Zhenggang; Zhao, Tongtong

    2016-09-01

    An evaluation method based on the total variation model (TV) in wavelet domain is proposed for modeling optical properties of real photonic crystal fibers (PCFs). The TV model in wavelet domain is set up to suppress the noise of the original image effectively and rebuild the cross section images of real PCFs with high accuracy. The optical properties of three PCFs are evaluated, including two kinds of PCFs that supplied from the Crystal Fiber A/S and a homemade side-leakage PCF, by using the combination of the proposed model and finite element method. Numerical results demonstrate that the proposed method can obtain high noise suppression ratio and effectively reduce the noise of cross section images of PCFs, which leads to an accurate evaluation of optical properties of real PCFs. To the best of our knowledge, it is the first time to denoise the cross section images of PCFs with the TV model in the wavelet domain.

  10. Wavelet-based method for computing elastic band gaps of one-dimensional phononic crystals

    Institute of Scientific and Technical Information of China (English)

    YAN; ZhiZhong; WANG; YueSheng

    2007-01-01

    A wavelet-based method was developed to compute elastic band gaps of one-dimensional phononic crystals. The wave field was expanded in the wavelet basis and an equivalent eigenvalue problem was derived in a matrix form involving the adaptive computation of integrals of the wavelets. The method was then applied to a binary system. For comparison, the elastic band gaps of the same one-di- mensional phononic crystals computed with the wavelet method and the well- known plane wave expansion (PWE) method are both presented in this paper. The numerical results of the two methods are in good agreement while the computation costs of the wavelet method are much lower than that of PWE method. In addition, the adaptability of wavelets makes the method possible for efficient band gap computation of more complex phononic structures.

  11. Mechanisms of the degradation of Schottky-barrier photodiodes based on ZnS single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Korsunska, N. E.; Shulga, E. P.; Stara, T. R., E-mail: stara-t@ukr.net; Litvin, P. M.; Bondarenko, V. A. [National Academy of Sciences of Ukraine, Lashkarev Institute of Semiconductor Physics (Ukraine)

    2016-01-15

    The effect of ultraviolet (UV) illumination on the electrical and spectral characteristics of Schottky-barrier photodiodes based on ZnS single crystals is studied. It is found that irradiation deteriorates their photosensitivity and changes the current–voltage and capacitance–voltage characteristics and the surface profile of the blocking electrode. It is shown that the main reason for a decrease in the photosensitivity of the diodes is the photoinduced drift of mobile donors in the electric field of the barrier. This drift depends on the crystallographic orientation of the surface being irradiated. Another photoinduced process observed in the diodes is photolysis of the ZnS crystal. This process mainly determines the change in the electrical characteristics of the diodes and in the surface profile of the electrode at an insignificant change in the photosensitivity.

  12. Silicon-nanomembrane-based photonic crystal nanostructures for chip-integrated open sensor systems

    Science.gov (United States)

    Chakravarty, Swapnajit; Lai, Wei-Cheng; Zou, Yi; Lin, Cheyun; Wang, Xiaolong; Chen, Ray T.

    2011-11-01

    We experimentally demonstrate two devices on the photonic crystal platform for chip-integrated optical absorption spectroscopy and chip-integrated biomolecular microarray assays. Infrared optical absorption spectroscopy and biomolecular assays based on conjugate-specific binding principles represent two dominant sensing mechanisms for a wide spectrum of applications in environmental pollution sensing in air and water, chem-bio agents and explosives detection for national security, microbial contamination sensing in food and beverages to name a few. The easy scalability of photonic crystal devices to any wavelength ensures that the sensing principles hold across a wide electromagnetic spectrum. Silicon, the workhorse of the electronics industry, is an ideal platform for the above optical sensing applications.

  13. Ultra-wide acoustic band gaps in pillar-based phononic crystal strips

    Energy Technology Data Exchange (ETDEWEB)

    Coffy, Etienne, E-mail: etienne.coffy@femto-st.fr; Lavergne, Thomas; Addouche, Mahmoud; Euphrasie, Sébastien; Vairac, Pascal; Khelif, Abdelkrim [FEMTO-ST Institute, Université de Franche-Comté, UBFC, CNRS, ENSMM, UTBM, 15B Av. des Montboucons, F-25030 Besançon (France)

    2015-12-07

    An original approach for designing a one dimensional phononic crystal strip with an ultra-wide band gap is presented. The strip consists of periodic pillars erected on a tailored beam, enabling the generation of a band gap that is due to both Bragg scattering and local resonances. The optimized combination of both effects results in the lowering and the widening of the main band gap, ultimately leading to a gap-to-midgap ratio of 138%. The design method used to improve the band gap width is based on the flattening of phononic bands and relies on the study of the modal energy distribution within the unit cell. The computed transmission through a finite number of periods corroborates the dispersion diagram. The strong attenuation, in excess of 150 dB for only five periods, highlights the interest of such ultra-wide band gap phononic crystal strips.

  14. Studies of plastic crystal gel polymer electrolytes based on poly(vinylidene chloride-co-acrylonitrile)

    Science.gov (United States)

    Hambali, D.; Zainuddin, Z.; Supa'at, I.; Osman, Z.

    2016-02-01

    In this work, we have prepared systems of poly(vinylidene chloride-co-acrylonitrile) (PVdC-co-AN) based gel polymer electrolytes (GPEs) which are single plasticized-GPEs and double plasticized-GPEs. Both systems comprised plastic crystal succinonitrile SN to form plastic crystal gel polymer electrolyte (PGPE) films. The ionic conductivity of the PGPE films were analysed by means of a.c. impedance spectroscopy at room temperature as well as at the temperature range of 303 K to 353 K. The temperature dependence ionic conductivity was found to obey the VTF rule. To study the interactions among the constituents in the PGPEs, Fourier Transform Infrared Spectroscopy (FTIR) was carried out and hence, the complexation between them has also been confirmed.

  15. All-solid-state narrow-linewidth 455-nm blue laser based on Ti: sapphire crystal

    Institute of Scientific and Technical Information of China (English)

    Shankui Rong; Xiaolei Zhu; Weibiao Chen

    2009-01-01

    A compact, all-solid-state, narrow-linewidth, pulsed 455-nm blue laser based on Ti:sapphire crystal is developed. Pumped by a 10-Hz, frequency-doubled all-solid-state Nd:YAG laser and injection-seeded by an external cavity laser diode, the narrow-linewidth 910-nm laser with pulse width of 20 ns is obtained from a Tirsapphire laser. 3.43-mJ blue laser can be obtained from the laser system by frequency-doubling with BBO crystal. This research is very useful to determine the roadmap of developing the practical, high power blue laser. This kind of laser will have potential application for underwater communication.

  16. Sensors Based on Plasmonic-Photonic Coupling in Metallic Photonic Crystals

    Directory of Open Access Journals (Sweden)

    Zhaoguang Pang

    2012-09-01

    Full Text Available An optical sensor based on the coupling between the plasmonic and photonic resonance modes in metallic photonic crystals is investigated. Large-area metallic photonic crystals consisting of periodically arranged gold nanostructures with dimensions down to sub-100 nm are fabricated using solution-processible gold nanoparticles in combination with interference lithography or interference ablation, which introduces a variety of fabrication techniques for the construction of this kind of sensor device. Sensitivity of the plasmonic response of the gold nanostructures to the changes in the environmental refractive index is enhanced through the coupling between the narrow-band photonic resonance mode and the relatively broad-band plasmon resonance, which is recognized as a Fano-like effect and is utilized to explore sensors. Theoretical modeling shows the characterization and the optimization of the sensitivity of this kind of sensor device. Theoretical and experimental results are demonstrated for the approaches to improve the sensitivity of the sensor device.

  17. Construction of optical data processing systems based on optoelectronic liquid crystal elements

    Science.gov (United States)

    Tolstik, Alexei; Melnikova, Elena

    2005-11-01

    The methods for the optical signal conversion based on the optoelectronic system "relief grating - liquid crystal" and liquid-crystal (LC) cells using S- or twist-effect have been presented. New schemes forming the basis for realization of bistable LC devices, optoelectronic logic elements and systems of electrically-coupled LC elements intended for the production of laser oscillations at the constant input intensity have been proposed. It has been demonstrated that with the use of varying parameters of optoelectronic feedback one is enabled to set up both regular and chaotic intensity oscillations, to control the frequency and form of these oscillations, to realize functional changes of logic elements. The developed LC systems have been introduced into the educational practice of students mastering modem information techniques.

  18. Bovine serum albumin detection and quantitation based on capacitance measurements of liquid crystals

    Science.gov (United States)

    Lin, Chi-Hao; Lee, Mon-Juan; Lee, Wei

    2016-08-01

    Liquid crystal (LC)-based biosensing is generally limited by the lack of accurate quantitative strategies. This study exploits the unique electric capacitance properties of LCs to establish quantitative assay methods for bovine serum albumin (BSA) biomolecules. By measuring the voltage-dependent electric capacitance of LCs under an alternating-current field with increasing amplitude, positive correlations were derived between the BSA concentration and the electric capacitance parameters of LCs. This study demonstrates that quantitative analysis can be achieved in LC-based biosensing through electric capacitance measurements extensively employed in LCD research and development.

  19. Bimolecular crystals with an intercalated structure improve poly(p-phenylenevinylene)-based organic photovoltaic cells.

    Science.gov (United States)

    Lim, Kyung-Geun; Park, Jun-Mo; Mangold, Hannah; Laquai, Frédéric; Choi, Tae-Lim; Lee, Tae-Woo

    2015-01-01

    The exciton dissociation, recombination, and charge transport of bulk heterojunction organic photovoltaic cells (OPVs) is influenced strongly by the nanomorphology of the blend, such as the grain size and the molecular packing. Although it is well known that polymers based on amorphous poly(p-phenylenevinylene) (PPV) have a fundamental limit to their efficiency because of low carrier mobility, which leads to increased recombination and unbalanced charge extraction, herein, we demonstrate that the issue can be overcome by forming bimolecular crystals of an amorphous PPV-based polymer:phenyl-C61 -butyric acid methyl ester (PCBM) intercalated structure. We used amorphous poly(2,5-dioctyloxy-p-phenylene vinylene-alt-2',5'-thienylene vinylene) (PPVTV), which has a simple chemical structure. A reasonably high power conversion efficiency (∼3.5 %) was obtained, although the material has an intrinsically amorphous structure and a relatively large band gap (2.0 eV). We demonstrate a correlation between a well-ordered bimolecular crystal of PPVTV:PCBM and an improved hole mobility of a PPVTV:PCBM film compared to a pristine PPVTV film by using 2 D grazing incidence XRD and space-charge-limited current measurements. Furthermore, we show that the bimolecular crystal structure in high-performance OPVs is related to an optimum molecular packing, which is influenced by the PPVTV:PCBM blending ratio, side-chain length, and molecular weight of the PPVTV polymer. Improved charge transport in PPVTV:PCBM bimolecular crystals leads to a fast sweep out of charges and thus suppression of nongeminate recombination under the operating conditions.

  20. Relaxor-based ferroelectric single crystals: growth, domain engineering, characterization and applications.

    Science.gov (United States)

    Sun, Enwei; Cao, Wenwu

    2014-08-01

    techniques, domain engineering concept, and full-matrix property characterization all the way to device innovations. It outlines a truly encouraging story in materials science in the modern era. All key references are provided and 30 complete sets of material parameters for different types of relaxor-PT single crystals are listed in the Appendix. It is the intension of this review article to serve as a resource for those who are interested in basic research and practical applications of these relaxor-PT single crystals. In addition, possible mechanisms of giant piezoelectric properties in these domain-engineered relaxor-PT systems will be discussed based on contributions from polarization rotation and charged domain walls.

  1. Relaxor-based ferroelectric single crystals: growth, domain engineering, characterization and applications.

    Science.gov (United States)

    Sun, Enwei; Cao, Wenwu

    2014-08-01

    techniques, domain engineering concept, and full-matrix property characterization all the way to device innovations. It outlines a truly encouraging story in materials science in the modern era. All key references are provided and 30 complete sets of material parameters for different types of relaxor-PT single crystals are listed in the Appendix. It is the intension of this review article to serve as a resource for those who are interested in basic research and practical applications of these relaxor-PT single crystals. In addition, possible mechanisms of giant piezoelectric properties in these domain-engineered relaxor-PT systems will be discussed based on contributions from polarization rotation and charged domain walls. PMID:25061239

  2. Substructure based modeling of nickel single crystals cycled at low plastic strain amplitudes

    Science.gov (United States)

    Zhou, Dong

    In this dissertation a meso-scale, substructure-based, composite single crystal model is fully developed from the simple uniaxial model to the 3-D finite element method (FEM) model with explicit substructures and further with substructure evolution parameters, to simulate the completely reversed, strain controlled, low plastic strain amplitude cyclic deformation of nickel single crystals. Rate-dependent viscoplasticity and Armstrong-Frederick type kinematic hardening rules are applied to substructures on slip systems in the model to describe the kinematic hardening behavior of crystals. Three explicit substructure components are assumed in the composite single crystal model, namely "loop patches" and "channels" which are aligned in parallel in a "vein matrix," and persistent slip bands (PSBs) connected in series with the vein matrix. A magnetic domain rotation model is presented to describe the reverse magnetostriction of single crystal nickel. Kinematic hardening parameters are obtained by fitting responses to experimental data in the uniaxial model, and the validity of uniaxial assumption is verified in the 3-D FEM model with explicit substructures. With information gathered from experiments, all control parameters in the model including hardening parameters, volume fraction of loop patches and PSBs, and variation of Young's modulus etc. are correlated to cumulative plastic strain and/or plastic strain amplitude; and the whole cyclic deformation history of single crystal nickel at low plastic strain amplitudes is simulated in the uniaxial model. Then these parameters are implanted in the 3-D FEM model to simulate the formation of PSB bands. A resolved shear stress criterion is set to trigger the formation of PSBs, and stress perturbation in the specimen is obtained by several elements assigned with PSB material properties a priori. Displacement increment, plastic strain amplitude control and overall stress-strain monitor and output are carried out in the user

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

    Energy Technology Data Exchange (ETDEWEB)

    Chataigner, E.; Remy, L.

    1996-12-31

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

  4. Structure Prediction Based on Hydrophobic to Hydrophilic Volume Ratios in Small Molecule Amphiphilic Organic Crystals

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The structure type for the crystal of 4,4'-bis-(2-hydroxy-ethoxyl)-biphenyl 1 has been predicted by using the previously developed interfacial model for small organic molecules. Based on the calculated hydrophobic to hydrophilic volume of 1, this model predicts the crystal structure to be of lamellar or bicontinuous type, which has been confirmed by the X-ray single-crystal structure analysis (C20H26O6, monoclinic, P21/c, a = 16.084(1), b = 6.0103(4), c = 9.6410(7)(A), β = 103.014(2)°, V = 908.1(1)(A)3, Z = 2, Dc = 1.325 g/cm3, F(000)=388, μ = 0.097 mm-1, MoKα radiation, λ = 0.71073 (A), R = 0.0382 and wR = 0.0882 with I > 2σ(I) for 7121 reflections collected, 1852 unique reflections and 170 parameters). As predicted, the hydrophobic and hydrophilic portions of 1 form in the lamellae. The same interfacial model is applied to other amphilphilic small molecule organic systems for structural type prediction.

  5. Formation and crystallization kinetics of Nd-Fe-B-based bulk amorphous alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Qiong; Ge, Hongliang; Zhang, Pengyue; Li, Dongyun; Wang, Zisheng [China Jiliang University, Magnetism Key Laboratory of Zhejiang Province, Hangzhou (China)

    2014-06-15

    In order to improve the glass-forming ability (GFA) of Nd-Fe-B ternary alloys to obtain fully amorphous bulk Nd-Fe-B-based alloy, the effects of Mo and Y doping on GFA of the alloys were investigated. It was found that the substitution of Mo for Fe and Y for Nd enhanced the GFA of the Nd-Y-Fe-Mo-B alloys. It was also revealed that the GFA of the samples was optimized by 4 at.% Mo doping and increased with theYcontent. The fully amorphous structures were all formed in the Nd{sub 6-x}Y{sub x}Fe{sub 68}Mo{sub 4}B{sub 22} (x =1-5) alloy rods with 1.5 mm-diameter. After subsequent crystallization, the devitrified Nd{sub 3}Y{sub 3}Fe{sub 68}Mo{sub 4}B{sub 22} alloy rod exhibited a uniform distribution of grains with a coercivity of 364.1 kA/m. The crystallization behavior of Nd{sub 3}Y{sub 3}Fe{sub 68}Mo{sub 4}B{sub 22} BMG was investigated in isothermal situation. The Avrami exponent n determined by JAM plot is lower than 2.5, implying that the crystallization is mainly governed by a growth of particles with decreasing nucleation rate. (orig.)

  6. Synthesis and Crystal Structure of a Co(II) Complex with Schiff Base and Imidazole Ligand

    Institute of Scientific and Technical Information of China (English)

    WU Lian-Bin; HU Zi-Qiang; LAI Guo-Qiao

    2006-01-01

    The title compound, [Co(C3H4N2)2(C22H18N2O4)]·5H2O (Mr = 659.56), has been prepared and its crystal structure was determined by X-ray diffraction method. The crystal be- longs to monoclinic, space group P21/n, a = 9.6808(2), b = 26.7204(5), c = 12.7993(3)(A), β = 100.9340(10)o, V = 3250.75(12) (A)3, Z = 4, Dc = 1.348 g/cm3, μ= 0.586 mm-1, F(000) = 1380, S = 1.131, R = 0.0689 and wR = 0.1883 for 4782 observed reflections (I > 2σ(I)). The title crystal consists of Co(II) complex and lattice water molecules. The Co(II) complex assumes a distorted octahedral coordination geometry, formed by one Schiff base dianion phenylenediamine-3-me- thoxysali-cylaldehyde and two imidazole ligands. The π-π stacking interaction occurs between nearly parallel benzene rings of the neighboring complexes.

  7. Hybrid silica luminescent materials based on lanthanide-containing lyotropic liquid crystal with polarized emission

    Energy Technology Data Exchange (ETDEWEB)

    Selivanova, N.M., E-mail: natsel@mail.ru [Kazan National Research Technological University, 68 Karl Marx Str., Kazan 420015 (Russian Federation); Vandyukov, A.E.; Gubaidullin, A.T. [A.E. Arbuzov Institute of Organic and Physical Chemistry of the Kazan Scientific Center of the Russian Academy of Sciences, 8 Acad. Arbuzov Str., Kazan 420088 (Russian Federation); Galyametdinov, Y.G. [Kazan National Research Technological University, 68 Karl Marx Str., Kazan 420015 (Russian Federation)

    2014-11-14

    This paper represents the template method for synthesis of hybrid silica films based on Ln-containing lyotropic liquid crystal and characterized by efficient luminescence. Luminescence films were prepared in situ by the sol–gel processes. Lyotropic liquid crystal (LLC) mesophases C{sub 12}H{sub 25}O(CH{sub 2}CH{sub 2}O){sub 10}H/Ln(NO{sub 3}){sub 3}·6H{sub 2}O/H{sub 2}O containing Ln (III) ions (Dy, Tb, Eu) were used as template. Polarized optical microscopy, X-ray powder diffraction, and FT-IR-spectroscopy were used for characterization of liquid crystal mesophases and hybrid films. The morphology of composite films was studied by the atomic force microscopy method (AFM). The optical properties of the resulting materials were evaluated. It was found that hybrid silica films demonstrate significant increase of their lifetime in comparison with an LLC system. New effects of linearly polarized emission revealed for Ln-containing hybrid silica films. Polarization in lanthanide-containing hybrid composites indicates that silica precursor causes orientation of emitting ions. - Highlights: • We suggest a new simple approach for creating luminescence hybrid silica films. • Ln-containing hybrid silica films demonstrate yellow, green and red emissions. • Tb(III)-containing hybrid film have a high lifetime. • We report effects of linearly polarized emission in hybrid film.

  8. Redetermination of LaZn5 based on single crystal X-ray diffraction data

    Directory of Open Access Journals (Sweden)

    Igor Oshchapovsky

    2012-01-01

    Full Text Available The crystal structure of the already known binary title compound LaZn5 (lanthanum pentazinc (space group P6/mmm, Pearson symbol hP6, CaCu5 structure type has been redetermined from single-crystal X-ray diffraction data. In contrast to previous determinations based on X-ray powder data [Nowotny (1942. Z. Metallkd. 34, 247–253; de Negri et al. (2008. Intermetallics, 16, 168–178], where unit-cell parameters and assignment of the structure type were reported, the present study reveals anisotropic displacement parameters for all atoms. The crystal structure consists of three crytallographically distinct atoms. The La atom (Wyckoff site 1a, site symmetry 6/mmm is surrounded by 18 Zn atoms and two La atoms. The coordination polyhedron around one of the Zn atoms (Wyckoff site 2c, site symmetry -6m2 is an icosahedron made up from three La and nine Zn atoms. The other Zn atom (Wyckoff site 3g, site symmetry mmm is surrounded by four La and eight Zn atoms. Bonding between atoms is explored by means of the TB–LMTO–ASA (tight-binding linear muffin-tin orbital atomic spheres approximation program package. The positive charge density is localized around La atoms, and the negative charge density is around Zn atoms, with weak covalent bonding between the latter.

  9. Tunable Stokes laser generation based on the stimulated polariton scattering in KTiOPO₄ crystal.

    Science.gov (United States)

    Jiang, Shiqi; Chen, Xiaohan; Cong, Zhenhua; Zhang, Xingyu; Qin, Zengguang; Liu, Zhaojun; Wang, Weitao; Li, Ning; Fu, Qiang; Lu, Qingming; Zhang, Shaojun

    2015-07-27

    The tunable Stokes laser characteristics based on the stimulated polariton scattering in KTiOPO4 (KTP) crystal and the intracavity frequency doubling properties for the Stokes laser are investigated for the first time. When the pumping laser wavelength is 1064.2 nm, and the angle between the pumping and Stokes beams outside the KTP crystal changes from 1.875° to 6.750°, the obtained tunable Stokes laser wavelength varies discontinuously from 1076.5 nm to 1091.4 nm with four gaps. When the pumping pulse energy is 120.0 mJ, the maximum Stokes pulse energy is 46.5 mJ obtained at the wavelength of 1086.6 nm. By inserting a LiB3O5 (LBO) crystal into the cavity, the obtained frequency-doubled laser wavelength is inconsecutive tunable from 538.5 nm to 543.8 nm. The maximum frequency-doubled laser pulse energy is 15.9 mJ at the wavelength of 543.5 nm. PMID:26367675

  10. Solidification and crystallization properties of CaO-SiO2-Na2O based mold fluxes

    Institute of Scientific and Technical Information of China (English)

    Sheng-ping He; Qian Wang; Dan Xie; Chu-shao Xu; Z.S.Li; K.C. Mills

    2009-01-01

    Crystallization properties play an important role in keeping a smooth running of continuous casting process and high sur-face quality of cast strands. To reduce fluorine pollution in slag, a new type of CaO-SiO2-Na2O (CSN) based mold flux was studied. The solidification and crystallization properties, including crystallization temperature, crystallization ratio and solidification minera-graphy, were measured, which were compared with the CaO-SiO2-CaF2 (GF) mold flux. The results show that the crystallization performance is equal to the high fluoride mold powder and CSN can be used for peritectic steel grades sensitive to longitudinal cracking in continuous casting.

  11. Mechanism Analysis of the Inverse Doppler Effect in Two-Dimensional Photonic Crystal based on Phase Evolution

    Science.gov (United States)

    Jiang, Qiang; Chen, Jiabi; Wang, Yan; Liang, Binming; Hu, Jinbing; Zhuang, Songlin

    2016-04-01

    Although the inverse Doppler effect has been observed experimentally at optical frequencies in photonic crystal with negative effective refractive index, its explanation is based on phenomenological theory rather than a strict theory. Elucidating the physical mechanism underlying the inverse Doppler shift is necessary. In this article, the primary electrical field component in the photonic crystal that leads to negative refraction was extracted, and the phase evolution of the entire process when light travels through a moving photonic crystal was investigated using static and dynamic finite different time domain methods. The analysis demonstrates the validity of the use of np (the effective refractive index of the photonic crystal in the light path) in these calculations, and reveals the origin of the inverse Doppler effect in photonic crystals.

  12. Microchip laser based on Yb:YAG/V:YAG monolith crystal

    Science.gov (United States)

    Nejezchleb, Karel; Šulc, Jan; Jelínková, Helena; Škoda, Václav

    2016-03-01

    V:YAG crystal was investigated as a passive Q-switch of longitudinally diode-pumped microchip laser, emitting radiation at wavelength 1030.5 nm. This laser was based on diffusion bonded monolith crystal (diameter 3 mm) which combines in one piece an active laser part (Yb:YAG crystal, 10 at.% Yb/Y, 3 mm long) and saturable absorber (V:YAG crystal, 2 mm long, initial transmission 86 % @ 1031 nm). The microchip resonator consisted of dielectric mirrors directly deposited on the monolith surfaces (pump mirror HT @ 968 nm and HR @ 1031 nm on Yb:YAG part, output coupler with reflection 55 % @ 1031 nm on the V:YAG part). For longitudinal CW pumping of Yb:YAG part, a fibre coupled (core diameter 100 μm, NA = 0.22, emission @ 968 nm) laser diode was used. The laser threshold was 3.8W. The laser slope efficiency for output mean in respect to incident pumping was 16 %. The linearly polarized generated transversal intensity beam profile was close to the fundamental Gaussian mode. The generated pulse length, stable and mostly independent on pumping power, was equal to 1.3 ns (FWHM). The single pulse energy was increasing with the pumping power and for the maximum pumping 9.7W it was 78 μJ which corresponds to the pulse peak-power 56 kW. The maximum Yb:YAG/V:YAG microchip laser mean output power of 1W was reached without observable thermal roll-over. The corresponding Q-switched pulses repetition rate was 13.1 kHz.

  13. Polarization Beam Splitter Based on a Self-Collimation Michelson Interferometer in a Silicon Photonic Crystal

    Institute of Scientific and Technical Information of China (English)

    CHEN Xi-Yao; LIN Gui-Min; LI Jun-Jun; XU Xiao-Fu; JIANG Jun-Zhen; QIANG Ze-Xuan; QIU Yi-Shen; LI Hui

    2012-01-01

    A polarization beam splitter based on a self-collimation Michelson interferometer (SMI) in a hole-type silicon photonic crystal is proposed and numerically demonstrated.Utilizing the polarization dependence of the transmission spectra of the SMI and polarization peak matching method,the SMI can work as a polarization beam splitter (PBS) by selecting an appropriate path length difference in the structure.Based on its novel polarization beam splitting mechanics,the polarization extinction ratios (PERs) for TM and TE modes are as high as 18.4 dB and 24.3 dB,respectively.Since its dimensions are only several operating wavelengths,the PBS may have practical applications in photonic integrated circuits.%A polarization beam splitter based on a self-collimation Michelson interferometer (SMI) in a hole-type silicon photonic crystal is proposed and numerically demonstrated. Utilizing the polarization dependence of the transmission spectra of the SMI and polarization peak matching method, the SMI can work as a polarization beam splitter (PBS) by selecting an appropriate path length difference in the structure. Based on its novel polarization beam splitting mechanics, the polarization extinction ratios (PERs) for TM and TE modes are as high as 18.4 dB and 24.3 dB, respectively. Since its dimensions are only several operating wavelengths, the PBS may have practical applications in photonic integrated circuits.

  14. Fabrication of fully undercut ZnO-based photonic crystal membranes with 3D optical confinement

    Science.gov (United States)

    Hoffmann, Sandro Phil; Albert, Maximilian; Meier, Cedrik

    2016-09-01

    For studying nonlinear photonics, a highly controllable emission of photons with specific properties is essential. Two-dimensional photonic crystals (PhCs) have proven to be an excellent candidate for manipulating photon emission due to resonator-based effects. Additionally, zinc oxide (ZnO) has high susceptibility coefficients and therefore shows pronounced nonlinear effects. However, in order to fabricate such a cavity, a fully undercut ZnO membrane is required, which is a challenging problem due to poor selectivity of the known etching chemistry for typical substrates such as sapphire or ZnO. The aim of this paper is to demonstrate and characterize fully undercut photonic crystal membranes based on a thin ZnO film sandwiched between two layers of silicon dioxide (SiO2) on silicon substrates, from the initial growth of the heterostructure throughout the entire fabrication process. This process leads to a fully undercut ZnO-based membrane with adjustable optical confinement in all three dimensions. Finally, photonic resonances within the tailored photonic band gap are achieved due to optimized PhC-design (in-plane) and total internal reflection in the z-direction. The presented approach enables a variety of photon based resonator structures in the UV regime for studying nonlinear effects, including photon-exciton coupling and all-optical switching.

  15. Switching behaviour of nonlinear Mach–Zehnder interferometer based on photonic crystal geometry

    Indian Academy of Sciences (India)

    Man Mohan Gupta; S Medhekar

    2014-06-01

    Nonlinear Mach–Zehnder interferometer (NMZI) created with photonic crystal waveguides (PCW) and with Kerr-type nonlinearity has been investigated in this paper. The NMZI has been simulated using two-dimensional finite difference time domain (2D-FDTD) method. Input verses output (I/O) characteristics have been obtained for different lengths of the nonlinear arm, nonlinear coefficients of the nonlinear arm, wavelengths of the input beam, sizes of defect rods and NMZI offset. The results obtained are compared with earlier published results of NMZI created with conventional step index waveguides (SIW). It is shown that all useful features of light switching offered by SIW-based NMZIs are also possible with PCW-based NMZIs of extremely small dimensions. Moreover, PCW-based NMZIs offer additional useful feature not available with SIW-based NMZIs.

  16. Computational crystallization.

    Science.gov (United States)

    Altan, Irem; Charbonneau, Patrick; Snell, Edward H

    2016-07-15

    Crystallization is a key step in macromolecular structure determination by crystallography. While a robust theoretical treatment of the process is available, due to the complexity of the system, the experimental process is still largely one of trial and error. In this article, efforts in the field are discussed together with a theoretical underpinning using a solubility phase diagram. Prior knowledge has been used to develop tools that computationally predict the crystallization outcome and define mutational approaches that enhance the likelihood of crystallization. For the most part these tools are based on binary outcomes (crystal or no crystal), and the full information contained in an assembly of crystallization screening experiments is lost. The potential of this additional information is illustrated by examples where new biological knowledge can be obtained and where a target can be sub-categorized to predict which class of reagents provides the crystallization driving force. Computational analysis of crystallization requires complete and correctly formatted data. While massive crystallization screening efforts are under way, the data available from many of these studies are sparse. The potential for this data and the steps needed to realize this potential are discussed.

  17. Computational crystallization.

    Science.gov (United States)

    Altan, Irem; Charbonneau, Patrick; Snell, Edward H

    2016-07-15

    Crystallization is a key step in macromolecular structure determination by crystallography. While a robust theoretical treatment of the process is available, due to the complexity of the system, the experimental process is still largely one of trial and error. In this article, efforts in the field are discussed together with a theoretical underpinning using a solubility phase diagram. Prior knowledge has been used to develop tools that computationally predict the crystallization outcome and define mutational approaches that enhance the likelihood of crystallization. For the most part these tools are based on binary outcomes (crystal or no crystal), and the full information contained in an assembly of crystallization screening experiments is lost. The potential of this additional information is illustrated by examples where new biological knowledge can be obtained and where a target can be sub-categorized to predict which class of reagents provides the crystallization driving force. Computational analysis of crystallization requires complete and correctly formatted data. While massive crystallization screening efforts are under way, the data available from many of these studies are sparse. The potential for this data and the steps needed to realize this potential are discussed. PMID:26792536

  18. Protein Crystallization

    Science.gov (United States)

    Chernov, Alexander A.

    2005-01-01

    Nucleation, growth and perfection of protein crystals will be overviewed along with crystal mechanical properties. The knowledge is based on experiments using optical and force crystals behave similar to inorganic crystals, though with a difference in orders of magnitude in growing parameters. For example, the low incorporation rate of large biomolecules requires up to 100 times larger supersaturation to grow protein, rather than inorganic crystals. Nucleation is often poorly reproducible, partly because of turbulence accompanying the mixing of precipitant with protein solution. Light scattering reveals fluctuations of molecular cluster size, its growth, surface energies and increased clustering as protein ages. Growth most often occurs layer-by-layer resulting in faceted crystals. New molecular layer on crystal face is terminated by a step where molecular incorporation occurs. Quantitative data on the incorporation rate will be discussed. Rounded crystals with molecularly disordered interfaces will be explained. Defects in crystals compromise the x-ray diffraction resolution crucially needed to find the 3D atomic structure of biomolecules. The defects are immobile so that birth defects stay forever. All lattice defects known for inorganics are revealed in protein crystals. Contribution of molecular conformations to lattice disorder is important, but not studied. This contribution may be enhanced by stress field from other defects. Homologous impurities (e.g., dimers, acetylated molecules) are trapped more willingly by a growing crystal than foreign protein impurities. The trapped impurities induce internal stress eliminated in crystals exceeding a critical size (part of mni for ferritin, lysozyme). Lesser impurities are trapped from stagnant, as compared to the flowing, solution. Freezing may induce much more defects unless quickly amorphysizing intracrystalline water.

  19. Analysis of crystallization process of selected Fe-based bulk metallic glasses

    Directory of Open Access Journals (Sweden)

    P. Sakiewicz

    2012-12-01

    Full Text Available Purpose: The paper mainly aims to present the influence of annealing temperature on structural changes and magnetic properties of selected Fe-based bulk metallic glasses with chemical composition of Fe43Co14Ni14B20Si5Nb4 (at.%.Design/methodology/approach: The investigated samples were cast in form of the rods with diameter of 1.5 mm by the pressure die casting method. The structure changes in function of annealing temperature were examined by X-ray diffraction (XRD and transmission electron microscopy (TEM methods. The crystallization behaviour of the studied alloy was also examined by differential scanning calorimetry (DSC. Magnetic measurements of annealed samples included the initial magnetic permeability and the magnetic permeability relaxation measurements.Findings: The annealing process at temperature range from 373 to 773 K caused a structural relaxation of tested material, which caused the atomic rearrangements and changes of physical properties in relation to as-cast state. The annealing at higher temperatures (823-923 K obviously caused a formation of α-Fe and iron borides crystalline phases. The increasing of annealing temperature significantly improved soft magnetic properties of examined alloy by increase the initial magnetic permeability and decrease the magnetic permeability relaxation.Practical implications: The investigation of the crystallization process of Fe-based metallic glasses is important for understanding the mechanisms of forming controlled microstructures of these materials with specific physical properties.Originality/value: A proper understanding of crystallization process of Fe-based bulk metallic glasses is still novel scientific problem.

  20. Widely tunable polarization maintaining photonic crystal fiber based parametric wavelength conversion.

    Science.gov (United States)

    Murray, Robert T; Kelleher, Edmund J R; Popov, Sergei V; Mussot, Arnaud; Kudlinski, Alexandre; Taylor, James R

    2013-07-01

    We report a near-visible parametric wavelength converter comprising a polarization-maintaining photonic crystal fiber (PM-PCF) pumped by a highly versatile diode-seeded master-oscillator power amplifier system based around 1.06 μm. The device is broadly tunable in wavelength (0.74-0.81 μm), pulse duration (0.2-1.5 ns) and repetition rate (1-30 MHz). A maximum anti-Stokes slope conversion efficiency of 14.9% is achieved with corresponding anti-Stokes average output powers of 845 mW, at a wavelength of 0.775 μm. PMID:23842368

  1. Polarization Beam Splitter Based on Self-Collimation Effect in Two-Dimensional Photonics Crystal

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jie; ZHAO De-Yin; ZHOU Chnan-Hong; JIANG Xun-Ya

    2007-01-01

    A photonic crystal polarization beam splitter based on the self-collimation effect is proposed. By means of the plane wave expansion method and the finite-difference time-domain method, we analyse the splitting mechanism in two alternative ways: performing a band gap structure analysis and simulating the field distribution. The results indicate that two beams of different polarizations can be split with an extinction ratio of nearly 20 dB in a wavelength range of 90nm. The splitter may have practical applications in integrated photonic circuits.

  2. Rod-like Schiff Base Magnetic Liquid Crystals Bearing Organic Radical

    Institute of Scientific and Technical Information of China (English)

    ZHENG, Min-Yan; AN, Zhong-Wei

    2006-01-01

    4 novel rod-like Schiff base magnetic liquid crystals have been prepared in which trans-bicyclohexyl or trans-cyclohexyl phenyl and biphenyl carboxylic acid phenol ester mesogenic cores with n-propyl and n-pentyl substituents were terminated by 4-amino-TEMPO (TEMPO=2,2,6,6-tetramethylpiperidine-l-oxyl). Of these compounds the silk-like and schlieren textures were found from 4c and 4d by POM (Polarizing Optical Microscope).DSC (Differential Scanning Calorimeter) measurements show that the mesophase exists from 4-6 ℃. EPR spectra reveal their paramagnetic properties.

  3. Some features of the technology of passive laser shutters based on GSGG crystals

    Science.gov (United States)

    Titov, A. N.; Krutova, L. I.; Ignatenkov, B. A.; Vetrov, V. N.

    2006-05-01

    This paper presents the results of work on improving the technology of passive laser shutters based on gallium scandium gadolinium garnet crystals doped with tetravalent chromium cations. It is shown that the behavior of the Cr4+ cations in a melt of a mix of oxides can be described by the Pfann equation, and the distribution factor of Cr4+ can be determined. It was possible to increase the utilization factor of the mix by a factor of 3.5 and to reduce the number of process operations by optimizing the technology.

  4. Photonic Crystal Waveguide Intersection Based on Self-Imaging of Multi-Mode Interference

    Institute of Scientific and Technical Information of China (English)

    DING Wei-Qiang; TANG Dong-Hua; CHEN Li-Xue; ZHAO Yuan; Liu Yan

    2007-01-01

    @@ A new mechanism of intersection formed by two line defect photonic crystal (PC) waveguides are numerically investigated using the finite-difference time-domain method. The results show that the normalized crosstalk is smaller than 10-4; the reflection is smaller than 10-3, and the transmission is larger than 0.999. The authors analyse the physical origins and find that a modified self-imaging process in the intersected multi-mode region is the main reason of the excellent performance. This kind of multi-mode interference based intersection may find potential applications in PC optical circuits.

  5. An efficient optical biochemical sensor based on a polyatomic photonic crystal ring resonator

    Science.gov (United States)

    Wang, Daobin; Liu, Yanjun; Yuan, Lihua; Lei, Jingli; Li, Xiaoxiao; wu, Gang; Hou, Shanglin

    2016-08-01

    In this paper, we introduce and investigate a design concept for a polyatomic photonic crystal ring resonator (PCRR). In contrast to conventional sensors, this PCRR comprises two different branching waveguides (WG), which are all oriented in the same lattice direction, but with different optical propagation properties due to the binary nature of the diatomic square lattice. Based on this new scheme, an on-chip biochemical sensor is proposed. Electromagnetic analysis, PWE and FDTD numerical techniques, were used to investigate the sensing performance. Our results show that such a sensor can efficiently detect small changes in the refractive index within the sensing area.

  6. Modeling of pressure sensors based on two-dimensional photonic crystals

    Institute of Scientific and Technical Information of China (English)

    Xuehui XIONG; Ping LU; Deming LIU

    2009-01-01

    A pressure sensor based on the two-dimensional photonic crystal (2D PC) has been proposed. Under the condition of different pressure, the photonic band gap of the sensor has been studied by means of the plane wave expansion method (PWM). The results show that there is a good linear relation between the cutoff wavelength and the pressure. Apart from being easily implemented, the presented 2D PC pressure sensor holds many characteristics such as high-pressure sensitivity and convenience in achieving demanded pressure range.

  7. Synthesis, crystal structures and photoluminescence of anthracen- and pyrene-based coumarin derivatives.

    Science.gov (United States)

    Zhang, Hui; Tong, Hao; Zhao, Yuling; Yu, Tianzhi; Zhang, Peng; Li, Jianfeng; Fan, Duowang

    2015-11-01

    Two new anthracen- and pyrene-based coumarin derivatives, 3-(4-(anthracen-10-yl)phenyl)coumarin (4) and 3-(4-(pyrene-1-yl)phenyl)coumarin (5), were synthesized and characterized by FT-IR, (1)H NMR, element analysis and single crystal X-ray crystallography. The UV-vis absorption and photoluminescence spectra of these coumarin derivatives were investigated. The results show that compound 4 and 5 exhibit blue and blue-green emissions, respectively, under ultraviolet light excitation. Compared with the compound 4, the emission peak of compound 5 was bathochromically shifted by about 80 nm due to the more planar structure and larger π-conjugation.

  8. Fabrication of liquid crystal based sensor for detection of hydrazine vapours

    Science.gov (United States)

    Nandi, Rajib; Singh, Sachin Kumar; Singh, Hemant Kumar; Singh, Bachcha; Singh, Ranjan K.

    2014-10-01

    A novel liquid crystal (LC) based sensor to detect trace level amount of hydrazine vapour has been developed. The LC 4‧-pentyl-4-biphenylcarbonitrile (5CB) doped with 0.5 wt% 4-decyloxy benzaldehyde (DBA) shows dark to bright optical texture upon exposure of hydrazine vapours as revealed by polarizing optical microscopy under crossed polarizers. The hydrazine interacts with the doped DBA and form diimine compound which disrupt the orientation of aligned 5CB. The interaction between DBA and hydrazine has been also studied by Raman spectroscopy.

  9. The progress of optical parametric oscillator based on LiNbO3 crystal

    Science.gov (United States)

    Xia, Lin-zhong; Zhang, Chun-xiao

    2014-11-01

    The MgO:PPLN-based QPM OPO is one of the most important method to generate mid-infrared laser. In this paper we attempt to briefly overview the historic development of LiNbO3 crystal and introduce the theoretical foundation of MgO:PPLN-based QPM OPO. We subsequently give a analysis of different kinds of MgO:PPLN-based QPM OPO. The wavelength region of 3-5 μm (belonging to the mid-infrared) is important atmospheric window in the optical spectrum. The mid-infrared lasers have drawn enormous interest and obtained a variety of applications, such as, air pollution detection, optical fiber communication, military countermeasures, and so on. In recent years, along with the emergence of lots of nonlinear materials (such as AgGaS2 and AgGaSe2, KTP and KTA, ZnGeP2, LiIO3, LiNbO3), it's become easier to obtain mid-infrared lasers. Because of those new nonlinear materials can satisfy the follow conditions, large nonlinearity, transparency in operating wavelength range and high damage resistance. Among those nonlinear materials, the LiNbO3 (LN) crystal is one of the most suitable materials to be used to obtain mid-infrared laser.

  10. Polyethylene Maleate Copolyesters as Coating Materials for Piezoelectric Quartz Crystal-based Chemical Sensors

    Directory of Open Access Journals (Sweden)

    D. C. Gupta

    2005-10-01

    Full Text Available Polyethylene maleate (PEM was synthesised by direct polycondensation of maleic anhydride and ethylene glycol in toluene under reflux usingp-toluene sulphonic acid as a catalyst. Structure of PEM was further modified by varying nature of diols and acid components, chain length of glycols, incorporation of aromatic and fluorine groups in the chain. Formation of PEM was monitored by gas chromatography. The parameters like degree of polymerisation, number average molecular weight (Mn, and weight average molecular weight (Mw were calculated from the extent of reaction and stoichiometric ratio of the reactants. The number average molecular weight was also determined using Knauer vapour pressure osmometer. Cohesive energy, volume, and solubility parameters of PEM-based copolyesters were calculated by group contribution method. These PEM-based copolyesters’ have been evaluated as sorbent-coating materials for the detection of organ0 phosphorus(OPcompo using dimethylmethylphosphonate (DMMP as model compound and piezoelectric crystal detector. PEMbisphenol A is found to be the most sensitive and potential coating material for the detection of OP compounds using piezoelectric crystal detector. Potential PEM-based copolyesters have been characterised by viscosity, infrared spectroscopy, NMR spectroscopy, Mn and thermal stability.

  11. Fabrication and characterization of size-controlled single-crystal-like PZT nanofibers by sol–gel based electrospinning

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Juan; Gao, Qian; He, Haiyan; Li, Xiang, E-mail: xiang.li@zju.edu.cn; Ren, Zhaohui; Liu, Yong; Shen, Ge; Xu, Gang; Zhang, Xiwen; Han, Gaorong, E-mail: hgr@zju.edu.cn

    2013-12-05

    Highlights: •Single-crystal-like PZT nanofibers were fabricated by electrospinning and calcination. •Fiber diameter was precisely controlled by solution viscosity and electrospinning parameters. •Pyrolysis is a key factor for fabrication of single-crystal-like structure. -- Abstract: Size-controlled single-crystal-like lead zirconate titanate (PbZr{sub 0.52}Ti{sub 0.48}O{sub 3}, PZT) ceramic fibers have been successfully prepared by sol–gel based electrospinning and subsequent calcination process, and their morphology, crystal structure have been characterized at nanoscale. The fiber diameter can be precisely controlled from ∼50 to 540 nm by varying the PVP concentration and electrospinning process parameters. The crystal structure of the nanofibers pyrolyzed at 400 °C for 0.5 h and calcined at 650 °C for 2 h is proved to be single-crystal-like tetragonal perovskite phase. A formation mechanism is also discussed based on the thermal decomposition process, effect of the calcination and pyrolysis procedure, using the thermogravimetry/differential scanning caborimetry (TG/DSC), X-ray diffraction (XRD) and transmission electron microscopy (TEM). It is found that the pyrolysis procedure is a critical factor for the fabrication of single-crystal-like structure PZT nanofibers using electrospinning.

  12. High-performance single crystal organic field-effect transistors based on two dithiophene-tetrathiafulvalene (DT-TTF) polymorphs.

    Science.gov (United States)

    Pfattner, Raphael; Mas-Torrent, Marta; Bilotti, Ivano; Brillante, Aldo; Milita, Silvia; Liscio, Fabiola; Biscarini, Fabio; Marszalek, Tomasz; Ulanski, Jacek; Nosal, Andrzej; Gazicki-Lipman, Maciej; Leufgen, Michael; Schmidt, Georg; Molenkamp, Laurens W; Laukhin, Vladimir; Veciana, Jaume; Rovira, Concepció

    2010-10-01

    Solution prepared single crystal organic field-effect transistors (OFETs) combine low-cost with high performance due to structural ordering of molecules. However, in organic crystals polymorphism is a known phenomenon, which can have a crucial influence on charge transport. Here, the performance of solution-prepared single crystal OFETs based on two different polymorphs of dithiophene-tetrathiafulvalene, which were investigated by confocal Raman spectroscopy and X-ray diffraction, are reported. OFET devices prepared using different configurations show that both polymorphs exhibited excellent device performance, although the -phase revealed charge carrier mobility between two and ten times higher in accordance to the closer stacking of the molecules.

  13. Effects of temperature and solvent concentration on the solvent crystallization of palm-based dihydroxystearic acid with isopropyl alcohol

    Institute of Scientific and Technical Information of China (English)

    Gregory F.L.Koay; Teong-Guan Chuah; Sumaiya Zainal-Abidin; Salmiah Ahmad; Thomas S.Y.Choong

    2012-01-01

    Palm-based dihydroxystearic acid of 69.55% purity was produced in a 500-kg-per-batch operation pilot plant and purified through solvent crystallization in a custom fabricated simultaneous batch crystallizer unit.The effects of temperature and solvent concentration on yield,particle size distribution and purity were studied.The purity was higher,while the yield and particle size were lower and smaller,respectively,at higher temperature and solvent concentration.The solvent crystallization process efficiency was rated at 66-69% when carried out with 70-80% isopropyl alcohol at 20 ℃.

  14. Ground-based research of crystal growth of II-VI compound semiconductors by physical vapor transport

    Science.gov (United States)

    Volz, M. P.; Gillies, D. C.; Szofran, F. R.; Lehoczky, S. L.; Su, Ching-Hua; Sha, Yi-Gao; Zhou, W.; Dudley, M.; Liu, Hao-Chieh; Brebrick, R. F.; Wang, J. C.

    1994-01-01

    Ground-based investigation of the crystal growth of II-VI semiconductor compounds, including CdTe, CdS, ZnTe, and ZnSe, by physical vapor transport in closed ampoules was performed. The crystal growth experimental process and supporting activities--preparation and heat treatment of starting materials, vapor partial pressure measurements, and transport rate measurements are reported. The results of crystal characterization, including microscopy, microstructure, optical transmission photoluminescence, synchrotron radiation topography, and chemical analysis by spark source mass spectrography, are also discussed.

  15. Highly sensitive and fast response gas sensor based on a light reflection at the glass-photonic crystal interface

    Science.gov (United States)

    Kuchyanov, A. S.; Chubakov, P. A.; Plekhanov, A. I.

    2015-09-01

    We develop a versatile gas sensor based on the condition for total internal reflection at the glass-photonic crystal interface and corresponding detection scheme for rapid and precise measurement of vapors. The sensor consists of a vapor sensitive photonic crystal film as a Fabry-Perot etalon coated on a solid substrate (e.g., large face of a glass prism or glass slide). Such scheme and specific physicochemical properties of submicron silica particles provide photonic crystal sensor selectivity due to the capillary condensation of ammonia vapor with a sensitivity of 1 ppm with a response time of 100 ms.

  16. Holographic three-dimensional display and hologram calculation based on liquid crystal on silicon device [invited].

    Science.gov (United States)

    Li, Junchang; Tu, Han-Yen; Yeh, Wei-Chieh; Gui, Jinbin; Cheng, Chau-Jern

    2014-09-20

    Based on scalar diffraction theory and the geometric structure of liquid crystal on silicon (LCoS), we study the impulse responses and image depth of focus in a holographic three-dimensional (3D) display system. Theoretical expressions of the impulse response and the depth of focus of reconstructed 3D images are obtained, and experimental verifications of the imaging properties are performed. The results indicated that the images formed by holographic display based on the LCoS device were periodic image fields surrounding optical axes. The widths of the image fields were directly proportional to the wavelength and diffraction distance, and inversely proportional to the pixel size of the LCoS device. Based on the features of holographic 3D imaging and focal depth, we enhance currently popular hologram calculation methods of 3D objects to improve the computing speed of hologram calculation.

  17. Ground Based Retrievals of Small Ice Crystals and Water Phase in Arctic Cirrus

    Science.gov (United States)

    Mishra, Subhashree; Mitchell, David L.; DeSlover, Daniel

    2009-03-01

    The microphysical properties of cirrus clouds are uncertain due to the problem of ice particles shattering at the probe inlet upon sampling. To facilitate better estimation of small ice crystal concentrations in cirrus clouds, a new ground-based remote sensing technique has been used in combination with in situ aircraft measurements. Data from the Mixed-Phase Arctic Cloud Experiment (M-PACE), conducted at the north slope of Alaska (winter 2004), have been used to test a new method for retrieving the liquid water path (LWP) and ice water path (IWP) in mixed phase clouds. The framework of the retrieval algorithm consists of the modified anomalous diffraction approximation or MADA (for mixed phase cloud optical properties), a radar reflectivity-ice microphysics relationship and a temperature-dependent ice particle size distribution (PSD) scheme. Cloud thermal emission measurements made by the ground-based Atmospheric Emitted Radiance Interferometer (AERI) yield information on the total water path (TWP) while reflectivity measurements from the Millimeter Cloud Radar (MMCR) are used to derive the IWP. The AERI is also used to indicate the concentration of small ice crystals (Dproperties of photon tunneling or wave resonance while the liquid water fraction is evaluated using classical Beer's law absorption. While this is still a work in progress, the anticipated products from this AERI-radar retrieval scheme are the IWP, LWP, small-to-large ice crystal number concentration ratio and effective diameter for cirrus, as well as the ice particle number concentration for a given ice water content (IWC).

  18. Secondary Crystal Growth on a Cracked Hydrotalcite-Based Film Synthesized by the Sol-Gel Method.

    Science.gov (United States)

    Lee, Wooyoung; Lee, Chan Hyun; Lee, Ki Bong

    2016-05-01

    The sol-gel synthesis method is an attractive technology for the fabrication of ceramic films due to its preparation simplicity and ease of varying the metal composition. However, this technique presents some limitations in relation to the film thickness. Notably, when the film thickness exceeds the critical limit, large tensile stresses occur, resulting in a cracked morphology. In this study, a secondary crystal growth method was introduced as a post-treatment process for Mg/Al hydrotalcite-based films synthesized by the sol-gel method, which typically present a cracked morphology. The cracked hydrotalcite-based film was hydrothermally treated for the secondary growth of hydrotalcite crystals. In the resulting film, hydrotalcite grew with a vertical orientation, and the gaps formed during the sol-gel synthesis were filled with hydrotalcite after the crystal growth. The secondary crystal growth method provides a new solution for cracked ceramic films synthesized by the sol-gel method.

  19. Self-assembling behavior in decane solution of potential wax crystal nucleators based on poly(co-olefins)

    OpenAIRE

    Schwahn, D.; Richter, D; Wright, P J; Symon, C.; Fetters, L.J.; Lin, M.

    2002-01-01

    The control of the precipitation and gelation of long chain paraffins from oil remains an enduring technological challenge regarding the processing and recovery of refined fuels and waxy crudes. Wax crystal modifiers based on polyethylene -poly(ethylene-propylene) (PE-PEP) diblock copolymers function as efficient nucleators for wax crystals in middle distillate fuels. These diblock polymers self-assemble in oil to form expansive platelike aggregates consisting of a PE core cloaked behind the ...

  20. Surface plasmon Raman scattering studies of liquid crystal anchoring on liquid-crystal-based self-assembled monolayers.

    Science.gov (United States)

    Critchley, Kevin; Cheadle, Edward M; Zhang, Hao-Li; Baldwin, Kurt J; Liu, Quanying; Cheng, Yaling; Fukushima, Hitoshi; Tamaki, Takashi; Batchelder, David N; Bushby, Richard J; Evans, Stephen D

    2009-11-26

    We studied the anchoring of 6CB on a series of self-assembled monolayers (SAMs) with a functional group that mimics that of the nematic liquid crystal (LC). The SAMs were first characterized by wetting, Fourier-transform infrared spectroscopy, and surface potential measurements. We found that, in two of these SAMs, the end group dipoles were oriented close to the normal of the surface and that these promoted homeotropic anchoring. In the case of the other SAM, the dipole was oriented parallel to the surface, and planar anchoring was obtained. Raman scattering by adsorbates on thin metal films is enhanced by the electromagnetic fields of surface plasmon polaritons (SPPs). Despite the inherent polarization of SPPs, there have been few reports in which SPP Raman scattering has been used to study molecular orientation. We have developed optical instrumentation to provide efficient excitation and collection of SPP Raman scattered light using attenuated total reflection geometry. The Kretschmann prism coupling configuration was used to excite SPPs on thin (500 A) gold films with adsorbed SAMs of alkanethiols in contact with thin films (50 microm) of the nematic liquid crystal 4'-hexylbiphenyl-4-carbonitrile (6CB, Merck). The anchoring and orientational wetting of the LC 6CB at the interface with omega-functionalized SAMs was studied using this arrangement. In agreement with the results of previous studies, a high-energy surface (-COOH) was found to promote planar anchoring, whereas a low-energy surface (-CF(3)) was found to induce homeotropic anchoring. PMID:19921953

  1. Synergistic effect of rhenium and ruthenium in nickel-based single-crystal superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Yu, X.X. [Department of Physics, Tsinghua University, Beijing 100084 (China); Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Wang, C.Y., E-mail: cywang@mail.tsinghua.edu.cn [Department of Physics, Tsinghua University, Beijing 100084 (China); Central Iron and Steel Research Institute, Beijing 100081 (China); Zhang, X.N. [Institute of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing 100124 (China); Yan, P. [Central Iron and Steel Research Institute, Beijing 100081 (China); Zhang, Z., E-mail: zezhang@zju.edu.cn [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)

    2014-01-05

    Highlights: • Re and Ru synergistic effects in nickel-based superalloys are investigated. • The Al site occupation of Re atom in the γ′ phase is observed directly. • The addition of Ru results in the repartitioning of Re to γ phase. -- Abstract: The microstructures of ternary Ni–Al–Re and quaternary Ni–Al–Re–Ru single-crystal alloys were investigated at atomic and electronic levels to clarify the synergistic effect of Re and Ru in nickel-based single-crystal superalloys. In the Ni–Al–Re alloy, it was directly observed that Re atom occupied the Al site of γ′ phase. In the Ni–Al–Re–Ru alloy, the mechanisms of Re repartition between γ and γ′ phases were proposed. In the dendritic cores, high concentrations of Re exceeded the solubility limit of γ′ phase and partitioned to γ phase, which led to the homogenization. In the interdendritic regions, Ru resulted in the repartitioning of Re to γ phase which was proved by transmission electron microscopy and first-principles calculations.

  2. Orientation dependence of secondary reaction zones in surface modified Ni-based single crystal superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Murakami, H.; Kuroda, S. [National Institute for Materials Science, Ibaraki (Japan). Thermal Spray Group, Materials Engineering Lab.; Sakai, T. [National Institute for Materials Science, Ibaraki (Japan). Thermal Spray Group, Materials Engineering Lab.]|[Tokyo Univ. (Japan). Dept. of Materials Engineering, Graduate School of Engineering; Shibata, M. [National Institute for Materials Science, Ibaraki (Japan). Thermal Spray Group, Materials Engineering Lab.]|[Chiba Institute of Technology, Narashino (Japan). Dept. of Mechanical Science and Engineering, Graduate School of Engineering; Yamaguchi, A. [National Institute for Materials Science, Ibaraki (Japan). Thermal Spray Group, Materials Engineering Lab.]|[Shibaura Institute of Technology, Tokyo (Japan). Dept. of Materials Science and Engineering, Faculty of Engineering

    2006-07-01

    Effects of surface treatments and coating conditions on microstructure changes of Ni-based superalloy substrates were investigated, with special attention to the orientation dependence. CoNiCrAlY (AMDRY 9954) powder was coated on Ni-based single crystal superalloy TMS-82+ by low pressure plasma spraying (LPPS). It was found that grit-blasted treatment drastically distorted the coherent {gamma}/{gamma}' microstructure of substrates, which accordingly promoted the uniform and accelerated the formation of secondary reaction zones (SRZ) by the post heat treatment at 1273 K for 30 min, where precipitation of topologically closed-packed (TCP) phases was observed. On the other hand, specimens without the grit-blast treatment had less amount of TCP precipitates, but showed preferred precipitation orientation along left angle 011 right angle {l_brace}100{r_brace} direction. Similar orientation dependence of SRZ formation was observed in the aluminized single crystal superalloy TMS-75. This orientation dependence of SRZ can occur in associate with the recrystallization of the substrate surface and subsequent interdiffusion of alloying elements. (orig.)

  3. CCSD(T)/CBS fragment-based calculations of lattice energy of molecular crystals

    Science.gov (United States)

    Červinka, Ctirad; Fulem, Michal; Růžička, Květoslav

    2016-02-01

    A comparative study of the lattice energy calculations for a data set of 25 molecular crystals is performed using an additive scheme based on the individual energies of up to four-body interactions calculated using the coupled clusters with iterative treatment of single and double excitations and perturbative triples correction (CCSD(T)) with an estimated complete basis set (CBS) description. The CCSD(T)/CBS values on lattice energies are used to estimate sublimation enthalpies which are compared with critically assessed and thermodynamically consistent experimental values. The average absolute percentage deviation of calculated sublimation enthalpies from experimental values amounts to 13% (corresponding to 4.8 kJ mol-1 on absolute scale) with unbiased distribution of positive to negative deviations. As pair interaction energies present a dominant contribution to the lattice energy and CCSD(T)/CBS calculations still remain computationally costly, benchmark calculations of pair interaction energies defined by crystal parameters involving 17 levels of theory, including recently developed methods with local and explicit treatment of electronic correlation, such as LCC and LCC-F12, are also presented. Locally and explicitly correlated methods are found to be computationally effective and reliable methods enabling the application of fragment-based methods for larger systems.

  4. Synthesis and Crystal Structure of a Novel Fe(Ⅲ) Schiff Base Complex

    Institute of Scientific and Technical Information of China (English)

    JIANG Guang-Qi; ZHANG Dai-Yu; YANG Zheng-Feng

    2012-01-01

    A novel Fe(Ⅲ) Schiff base complex,FeⅢ(HL) {H4L = 1,1,1,1-tetrakis[(salicylaldimino)methyl]methane},has been prepared and characterized by elemental analyses,IR spectrum,and single-crystal X-ray diffraction analysis.The crystal belongs to the monoclinic system,space group P21/n with a = 12.569(3),b = 12.955(3),c = 17.647(4) ,β = 91.896(9)°,V = 2871.9(1) 3,Z = 4,Dc = 1.391 g/cm3,F(000) = 1252.0,Mr = 601.45,R = 0.0383 and wR = 0.1025.The structural analysis reveals that the Fe(Ⅲ) ions are six-coordinated by imine nitrogen atoms and phenolic oxygen atoms form three pendant arms of Schiff base ligands,and one of the salicylaldimine chelating units remains uncoordinated.Discrete complex molecules were further assembled into 1D supramolecular aggregations by C-H…O hydrogen bonding and C-H…π interactions.

  5. An Electrochemical Quartz Crystal Microbalance Multisensor System Based on Phthalocyanine Nanostructured Films: Discrimination of Musts

    Directory of Open Access Journals (Sweden)

    Celia Garcia-Hernandez

    2015-11-01

    Full Text Available An array of electrochemical quartz crystal electrodes (EQCM modified with nanostructured films based on phthalocyanines was developed and used to discriminate musts prepared from different varieties of grapes. Nanostructured films of iron, nickel and copper phthalocyanines were deposited on Pt/quartz crystals through the Layer by Layer technique by alternating layers of the corresponding phthalocyanine and poly-allylamine hydrochloride. Simultaneous electrochemical and mass measurements were used to study the mass changes accompanying the oxidation of electroactive species present in must samples obtained from six Spanish varieties of grapes (Juan García, Prieto Picudo, Mencía Regadío, Cabernet Sauvignon, Garnacha and Tempranillo. The mass and voltammetric outputs were processed using three-way models. Parallel Factor Analysis (PARAFAC was successfully used to discriminate the must samples according to their variety. Multi-way partial least squares (N-PLS evidenced the correlations existing between the voltammetric data and the polyphenolic content measured by chemical methods. Similarly, N-PLS showed a correlation between mass outputs and parameters related to the sugar content. These results demonstrated that electronic tongues based on arrays of EQCM sensors can offer advantages over arrays of mass or voltammetric sensors used separately.

  6. Gels and lyotropic liquid crystals: using an imidazolium-based catanionic surfactant in binary solvents.

    Science.gov (United States)

    Cheng, Ni; Hu, Qiongzheng; Bi, Yanhui; Xu, Wenwen; Gong, Yanjun; Yu, Li

    2014-08-01

    The self-assembly behavior of an imidazolium-based catanionic surfactant, 1-butyl-3-methylimidazolium dodecylsulfate ([C4mim][C12H25SO4]), was investigated in water-ethylammonium nitrate (EAN) mixed solvents with different volume ratios. It is particular interesting that this simple surfactant could not only form lyotropic liquid crystals (LLC) with multimesophases, i.e., normal hexagonal (H1), lamellar liquid crystal (Lα), and reverse bicontinuous cubic phase (V2), in the water-rich environment but also act as an efficient low-molecular-weight gelator (LMWG) which gelated EAN-abundant binary media in a broad concentration range. The peculiar nanodisk cluster morphology of gels composed of similar bilayer units was first observed. FT-IR spectra and density functional theory (DFT) calculations reveal that strong H bonding and electrostatic interactions between EAN and the headgroups of [C4mim][C12H25SO4] are primarily responsible for gelation. The self-assembled gels displayed excellent mechanical strength and a thermoreversible sol-gel transition. It is for the first time that a rich variety of controllable ordered aggregates could be observed only by simply modulating the concentration of a single imidazolium-based catanionic surfactant or the ratio of mixed solvents. This environmentally friendly system is expected to have broad applications in various fields, such as materials science, drug delivery systems, and supramolecular chemistry.

  7. Syntheses and Crystal Structures of Two VO(IV) Schiff Base Complexes with Oxyammonia Ligand

    Institute of Scientific and Technical Information of China (English)

    李连之; 许涛; 王大奇; 牛梅菊; 冀海伟

    2004-01-01

    Two novel VO(IV) Schiff base complexes, VO(SALHA)2[SALHA: salicyaldehydeoxyammonia] and VO(o-VANHA)2 [o-VANHA: o-vanillin-oxyammonia], have been synthesized with salicyaldehyde or o-vanilline, hydroxylammonium chloride and vanadyl sulfate in absolute methanol, and their crystal structures were determined by single-crystal X-ray diffraction. The vanadium(IV) centers in both complexes are five-coordinate in a distorted square pyramidal geometry. VO(SALHA)2 (C14H12N2O5V, Mr = 339.20) crystallizes in the monoclinic system, space group P21/n with a = 14.716(9), b = 7.175(5), c = 14.716(9) A, β = 113.130(7), V = 1428.8(15) A3, Z = 4, Dc = 1.577 g/cm3, β = 0.71073 A, μ(MoKα) = 0.720 mm-1, F(000) = 692, the final R = 0.0466 and wR = 0.0829 for 1561 observed reflections (I > 2σ(I)). VO(o-VANHA)2 (C16H16N2O7V, Mr = 399.25) is of monoclinic, space group P21/n with a = 11.386(12), b = 10.405(10), c = 14.627(15) A, β = 93.654(19), V = 1729(3) A3, Z = 4, Dc = 1.533 g/cm3, β = 0.71073 A, μ(MoKα) = 0.615 mm-1, F(000) = 820, the final R = 0.0513 and wR = 0.1129 for 1235 observed reflections (I > 2σ(I)).

  8. Determination of cleavage planes and fracture characterization of Ni-based single crystal superalloys

    Science.gov (United States)

    Merrill, John M.; Wilcox, Roy C.

    1992-01-01

    The room temperature fracture behavior of the Ge Rene N-4, CMSX-2, and CMSX-4C single crystal Ni-based superalloys was studied. All crystals were grown along the (001) direction and tensile tested in both helium and hydrogen atmospheres. A stereoscopic technique developed for use with a scanning electron microscope was applied to determine cleavage planes. Planar gamma(') morphologies also were examined to help determine cleavage planes. Helium charged specimens failed on a number of planes including the (111), (110), and (320). In most cases planes of the (111)-type initiated at the notch region and became smaller and smaller as they moved in radially. Tensile strengths in helium averaged 1000 MPa higher than that of the hydrogen charged specimens. Specimens tested in hydrogen generally failed on (100)-type planes originating from the notch region. This (100) region comprised 60 to 80 percent of the total fracture surface on most samples and appeared as large flat planes perpendicular to the growth direction of the crystal. The interior regions contained (100)-type planes as well as (321), (320), (210), and (111)-types. Hydrogen charged specimens also showed a high percentage of large cracks oriented at 90 deg to one another, indicative of the (100)-type fracture. The Ge Rene N4 and the CMSX-4C samples contained 3-5 percent gamma/gamma(') eutectic, while the CMSX-2 samples had little or no gamma/gamma(') eutectic. The relationship between gamma/gamma(') eutectic and the fracture surface has not been fully determined, but it is thought that the gamma/gamma(') eutectic may serve as a possible trapping site for hydrogen.

  9. Modelling of Active Semiconductor Photonic Crystal Waveguides and Robust Designs based on Topology Optimization

    DEFF Research Database (Denmark)

    Chen, Yaohui; Wang, Fengwen; Ek, Sara;

    2011-01-01

    of the Lorentz reciprocity theorem. We highlight topology optimization as a systematic and robust design methodology considering manufacturing imperfections in optimizing active photonic crystal device performances, and compare the performance of standard photonic crystal waveguides with optimized structures....

  10. Crystal growth of new charge-transfer salts based on π-conjugated donor molecules

    Science.gov (United States)

    Morherr, Antonia; Witt, Sebastian; Chernenkaya, Alisa; Bäcker, Jan-Peter; Schönhense, Gerd; Bolte, Michael; Krellner, Cornelius

    2016-09-01

    New charge transfer crystals of π-conjugated, aromatic molecules (phenanthrene and picene) as donors were obtained by physical vapor transport. The melting behavior, optimization of crystal growth and the crystal structure are reported for charge transfer salts with (fluorinated) tetracyanoquinodimethane (TCNQ-Fx, x=0, 2, 4), which was used as acceptor material. The crystal structures were determined by single-crystal X-ray diffraction. Growth conditions for different vapor pressures in closed ampules were applied and the effect of these starting conditions for crystal size and quality is reported. The process of charge transfer was investigated by geometrical analysis of the crystal structure and by infrared spectroscopy on single crystals. With these three different acceptor strengths and the two sets of donor materials, it is possible to investigate the distribution of the charge transfer systematically. This helps to understand the charge transfer process in this class of materials with π-conjugated donor molecules.

  11. Crystal Growth of new charge-transfer salts based on $\\pi$-conjugated molecules

    CERN Document Server

    Morherr, Antonia; Chernenkaya, Alisa; Bäcker, Jan-Peter; Schönhense, Gerd; Bolte, Michael; Krellner, Cornelius

    2016-01-01

    New charge transfer crystals of $\\pi$-conjugated, aromatic molecules (phenanthrene and picene) as donors were obtained by physical vapor transport. The melting behavior, optimization of crystal growth and the crystal structure is reported for charge transfer salts with (fluorinated) tetracyanoquinodimethane (TCNQ-F$_x$, x=0, 2, 4), which was used as acceptor material. The crystal structures were determined by single-crystal X-ray diffraction. Growth conditions for different vapor pressures in closed ampules were applied and the effect of these starting conditions for crystal size and quality is reported. The process of charge transfer was investigated by geometrical analysis of the crystal structure and by infrared spectroscopy on single crystals. With these three different acceptor strengths and the two sets of donor materials, it is possible to investigate the distribution of the charge transfer systematically. This helps to understand the charge transfer process in this class of materials with $\\pi$-conjug...

  12. Novel magnetic field sensor based on magnetic fluids infiltrated dual-core photonic crystal fibers

    Science.gov (United States)

    Li, Jianhua; Wang, Rong; Wang, Jingyuan; Zhang, Baofu; Xu, Zhiyong; Wang, Huali

    2014-03-01

    Novel magnetic field sensor based on magnetic fluids infiltrated dual-core Photonic Crystal Fibers (PCFs) is proposed in this paper. Inside the cross-section of the designed PCFs, the two fiber cores filled with magnetic fluids (Fe3O4) are separated by an air hole, and then form two independent waveguides with mode coupling. The mode coupling under different magnetic field strength is investigated theoretically. A novel and simple magnetic field sensing system is proposed and its sensing performances have been studied numerically. The results show that the magnetic field sensor with 15-cm PCFs has a large sensing range and high sensitivity of 4.80 pm/Oe. It provides a new feasible method to design PCF-based magnetic field sensor.

  13. Rafting in single crystal nickel-base superalloys — An overview

    Indian Academy of Sciences (India)

    M Kamaraj

    2003-02-01

    Currently nickel-base single crystal (SX) superalloys are considered for the manufacture of critical components such as turbine blades, vanes etc., for aircraft engines as well as land-based power generation applications. Microstructure and high temperature mechanical properties are the major factors controlling the performance of SX superalloys. Rafting is an important phenomenon in these alloys which occurs during high temperature creep. It is essential to understand the rafting mechanism, and its characteristics on high temperature properties before considering the advanced applications. In this review article, the thermodynamic driving force for rafting with and without stress is explained. The nature and influence of rafting on creep properties including pre-rafted conditions are discussed. In addition, the effect of stress state on $\\gamma /\\gamma'$ rafting, kinetics and morphological evolution are discussed with the recent experimental results.

  14. Investigation of the Band Structure of Graphene-Based Plasmonic Photonic Crystals

    Directory of Open Access Journals (Sweden)

    Pingping Qiu

    2016-09-01

    Full Text Available In this paper, one-dimensional (1D and two-dimensional (2D graphene-based plasmonic photonic crystals (PhCs are proposed. The band structures and density of states (DOS have been numerically investigated. Photonic band gaps (PBGs are found in both 1D and 2D PhCs. Meanwhile, graphene-based plasmonic PhC nanocavity with resonant frequency around 175 THz, is realized by introducing point defect, where the chemical potential is from 0.085 to 0.25 eV, in a 2D PhC. Also, the bending wvaguide and the beam splitter are realized by introducing the line defect into the 2D PhC.

  15. Ultrabroadband polarization splitter based on three-core photonic crystal fibers.

    Science.gov (United States)

    Lu, Wenliang; Lou, Shuqin; Wang, Xin; Wang, Liwen; Feng, Ruijuan

    2013-01-20

    An ultrabroadband polarization splitter based on three-core photonic crystal fiber (PCF) is proposed. Two fluorine-doped cores and an elliptical modulation core are introduced to achieve an excellent performance and an ultrawide bandwidth. Numerical results demonstrate that the polarization splitter based on three-core PCF has an extinction ratio as low as -20 dB bandwidth as great as 400 nm covering almost all communication bands (O, E, S, C, and L bands). Its Gaussian-like mode-field distributions and suitable effective mode areas make it highly compatible with the standard single-mode fibers. Due to using a uniform size of circular air holes and only one elliptical central air hole, the difficulty of fabrication can be decreased to some extent.

  16. Coupled stress-strain and electrical resistivity measurements on copper based shape memory single crystals

    Directory of Open Access Journals (Sweden)

    Gonzalez Cezar Henrique

    2004-01-01

    Full Text Available Recently, electrical resistivity (ER measurements have been done during some thermomechanical tests in copper based shape memory alloys (SMA's. In this work, single crystals of Cu-based SMA's have been studied at different temperatures to analyse the relationship between stress (s and ER changes as a function of the strain (e. A good consistency between ER change values is observed in different experiments: thermal martensitic transformation, stress induced martensitic transformation and stress induced reorientation of martensite variants. During stress induced martensitic transformation (superelastic behaviour and stress induced reorientation of martensite variants, a linear relationship is obtained between ER and strain as well as the absence of hys teresis. In conclusion, the present results show a direct evidence of martensite electrical resistivity anisotropy.

  17. Preparation and characterization of high performance Schiff-base liquid crystal diepoxide polymer

    International Nuclear Information System (INIS)

    Graphical abstract: The specific effects of highly conjugated Schiff-base moiety on thermal properties of the Schiff-base epoxy polymer were proposed first by us. From the point of view of structure-properties relationship, it can be considered that owing to the presence of the Schiff-base group, the high performance liquid crystal diepoxide polymer displayed improved thermal stability. Highlights: ► In this work, we first proposed that specific effects of highly conjugated Schiff-base moiety on thermal properties of the Schiff-base epoxy polymer. ► As one aim of this study, the thermal and thermal-oxidative stabilities of the thermosets were studied by TGA under nitrogen and under air. ► The second aim of this study was to further understand the thermal degradation mechanism. ► For thermal degradation mechanism of this polymer under nitrogen, TG-IR was used to investigate volatile components, and SEM/EDS was used to explore morphologies and chemical components of the residual char. ► From the point of view of structure-properties relationship, it can be considered that owing to the presence of the Schiff-base group, the high performance liquid crystal diepoxide polymer displayed the improved thermal stability. - Abstract: A novel Schiff-base liquid crystal diepoxide polymer was prepared via a thermal copolymerization of a Schiff-base epoxy monomer (PBMBA) with a diamine co-monomer (MDA). We first proposed that specific effects of highly conjugated Schiff-base moiety on thermal properties of the Schiff-base epoxy polymer (PBMBA/MDA). Thermal degradation behavior of the polymer was characterized using thermogravimetric analysis (TGA) under nitrogen and under air, respectively. Thermogravimetric data obtained from TGA under nitrogen and under air reveal that PBMBA/MDA exhibits higher thermal stability compared with bisphenol-A type epoxy polymer (DGEBA/MDA) and other mesogene-containing epoxy polymer. It is worth pointing out that the outstanding residual

  18. Performance characteristics of thermal neutron detectors based on Li6Y(BO3)3:Ce single crystals

    Science.gov (United States)

    Singh, A. K.; Tyagi, M.; Singh, S. G.; Tiwari, B.; Desai, D. G.; Sen, S.; Desai, S. S.; Ghodke, S. S.; Gadkari, S. C.

    2015-12-01

    Crack-free single crystals of Ce doped Li6Y(BO3)3 (LYBO:Ce) have been grown using the Czochralski technique. Grown crystals were characterized for their optical and scintillation characteristics to explore their potential as neutron detectors. Scintillator detectors based on LYBO:Ce crystal were used successfully to record the pulse height spectra from various neutron sources in the flux range from 10 n/cm2/s to 107 n/cm2/s. The detection efficiency for thermal neutrons was found to be over 80% for a 2 mm thick LYBO:Ce crystal. The scintillation decay times measured for neutron and gamma radiations were about 27 ns and 49 ns, respectively.

  19. Effect of high-energy heavy ion irradiation on the crystallization kinetics of Co-based metallic glasses

    Indian Academy of Sciences (India)

    Rohit Jain; Deepika Bhandari; N S Saxena; S K Sharma; A Tripathi

    2001-02-01

    Differential scanning calorimeter (DSC) is employed to study the crystallization kinetics of irradiated (at three different fluences with high-energy heavy ion; Ni11+ of 150 MeV) specimens of two Co-based metallic glasses. It is found that the crystallization process in both the glasses is completed in two phases. The DSC data have been analysed in terms of kinetic parameters viz. activation energy (), Avrami exponent (), dimensionality of growth (), using two different theoretical models. The results obtained have been compared with that of virgin samples. The lower activation energy in case of second crystallization occurring at higher temperature indicates the easier nucleation of second phase. The abnormally high value of Avrami exponent in Co–Ni glass indicates very high nucleation rate during first crystallization.

  20. High-power nanosecond optical parametric oscillator based on a long LiB 3O 5 crystal

    Science.gov (United States)

    Li, H. Q.; Zhang, H. B.; Bao, Z.; Zhang, J.; Sun, Z. P.; Kong, Y. P.; Bi, Y.; Lin, X. C.; Yao, A. Y.; Wang, G. L.; Hou, W.; Li, R. N.; Cui, D. F.; Xu, Z. Y.

    2004-03-01

    We report on a compact high average power optical parametric oscillator (OPO) pumped by an all-solid-state nanosecond 532 nm laser. Based on the merit of non-critically phase-matched crystal without walk-off effect, a 50-mm-long LiB 3O 5 (LBO) crystal is used as OPO nonlinear crystal to enhance the conversion efficiency and increase the output power. With the available mirror set, continuous tuning from 778 to 1036 nm for signal wave is obtained by changing LBO phase-matching temperature. The maximum average power of signal output is up to 9.4 W at 900 nm for pump power of 18 W inside the LBO crystal, corresponding to a conversion efficiency of 52% only for the signal output. This is, to the best of our knowledge, the highest signal average power generated by nanosecond OPO in single bulk LBO.

  1. Fast ellipsometric measurements based on a single crystal photo-elastic modulator.

    Science.gov (United States)

    Petkovšek, R; Petelin, Jaka; Možina, J; Bammer, F

    2010-09-27

    For quality control in high volume manufacturing of thin layers and for tracking of physical and chemical processes, ellipsometry is a common measurement technology. For such kinds of applications we present a novel approach of fast ellipsometric measurements. Instead of a conventional setup that uses a standard photo-elastic modulator, we use a 92 kHz Single Crystal Photo-Elastic Modulator (SCPEM), which is a LiTaO3 crystal with a size of 28 × 9 × 4 mm. This small, simple, and cost-effective solution also offers the advantage of direct control of the retardation via the current amplitude, which is important for repeatability of the measurements. Instead of a Lock-In Amplifier, an automated digital processing based on a fast analog to digital converter controlled by a highly flexible Field Programmable Gate Array is used. This and the extremely compact and efficient polarization modulation allow fast ellipsometric testing where the upper limit of measurement rates is mainly limited by the desired accuracy and repeatability of the measurements. The standard deviation that is related to the repeatability +/-0.002° for dielectric layers can be easily reached. PMID:20941038

  2. Detection of Myoglobin with an Open-Cavity-Based Label-Free Photonic Crystal Biosensor

    Directory of Open Access Journals (Sweden)

    Bailin Zhang

    2013-01-01

    Full Text Available The label-free detection of one of the cardiac biomarkers, myoglobin, using a photonic-crystal-based biosensor in a total-internal-reflection configuration (PC-TIR is presented in this paper. The PC-TIR sensor possesses a unique open optical microcavity that allows for several key advantages in biomolecular assays. In contrast to a conventional closed microcavity, the open configuration allows easy functionalization of the sensing surface for rapid biomolecular binding assays. Moreover, the properties of PC structures make it easy to be designed and engineered for operating at any optical wavelength. Through fine design of the photonic crystal structure, biochemical modification of the sensor surface, and integration with a microfluidic system, we have demonstrated that the detection sensitivity of the sensor for myoglobin has reached the clinically significant concentration range, enabling potential usage of this biosensor for diagnosis of acute myocardial infarction. The real-time response of the sensor to the myoglobin binding may potentially provide point-of-care monitoring of patients and treatment effects.

  3. Detection of anthrax lef with DNA-based photonic crystal sensors

    Science.gov (United States)

    Zhang, Bailin; Dallo, Shatha; Peterson, Ralph; Hussain, Syed; Weitao, Tao; Ye, Jing Yong

    2011-12-01

    Bacillus anthracis has posed a threat of becoming biological weapons of mass destruction due to its virulence factors encoded by the plasmid-borne genes, such as lef for lethal factor. We report the development of a fast and sensitive anthrax DNA biosensor based on a photonic crystal structure used in a total-internal-reflection configuration. For the detection of the lef gene, a single-stranded DNA lef probe was biotinylated and immobilized onto the sensor via biotin-streptavidin interactions. A positive control, lef-com, was the complementary strand of the probe, while a negative control was an unrelated single-stranded DNA fragment from the 16S rRNA gene of Acinetobacter baumannii. After addition of the biotinylated lef probe onto the sensor, significant changes in the resonance wavelength of the sensor were observed, resulting from binding of the probe to streptavidin on the sensor. The addition of lef-com led to another significant increase as a result of hybridization between the two DNA strands. The detection sensitivity for the target DNA reached as low as 0.1 nM. In contrast, adding the unrelated DNAs did not cause an obvious shift in the resonant wavelength. These results demonstrate that detection of the anthrax lef by the photonic crystal structure in a total-internal-reflection sensor is highly specific and sensitive.

  4. Full-optical tunable add/drop filter based on nonlinear photonic crystal ring resonators

    Science.gov (United States)

    Mansouri-Birjandi, Mohammad Ali; Tavousi, Alireza; Ghadrdan, Majid

    2016-09-01

    Here, we propose a full-optical tunable Add/Drop filter based on single (SR) and double-vertically (DR) aligned Kerr-like nonlinear photonic crystal ring resonators (PCRRs). Silicon (Si) nano-crystal is used as the nonlinear material inside and outside of PCRRs. The minimum optical power required to turn-on/turn-off the SR and DR filters are 2000 mW/μm2, and 150 mW/μm2, respectively. We believe since the DR filter has a higher Q-factor rather than SR and also since the optical power reads more nonlinear rods with a longer time to pass the structure, thus the optical power required is much lower (10 folds). In addition, the minimum power required to 1 nm redshift the center operating wavelength of SR filter is 125 mW/μm2 (i.e. ΔnNL = 0.005) and for DR is as low as 8 mW/μm2. Performance of the Add/Drop filter structure is simulated by means of finite difference time domain (FDTD) method, in which the simulations showed an ultra-compact size structure with promising ultrafast tune-ability speeds.

  5. A Photonic Crystal Laser from Solution Based Organo-Lead Iodide Perovskite Thin Films.

    Science.gov (United States)

    Chen, Songtao; Roh, Kwangdong; Lee, Joonhee; Chong, Wee Kiang; Lu, Yao; Mathews, Nripan; Sum, Tze Chien; Nurmikko, Arto

    2016-04-26

    Perovskite semiconductors are actively investigated for high performance solar cells. Their large optical absorption coefficient and facile solution-based, low-temperature synthesis of thin films make perovskites also a candidate for light-emitting devices across the visible and near-infrared. Specific to their potential as optical gain medium for lasers, early work has demonstrated amplified spontaneous emission and lasing at attractively low thresholds of photoexcitation. Here, we take an important step toward practically usable perovskite lasers where a solution-processed thin film is embedded within a two-dimensional photonic crystal resonator. We demonstrate high degree of temporally and spatially coherent lasing whereby well-defined directional emission is achieved near 788 nm wavelength at optical pumping energy density threshold of 68.5 ± 3.0 μJ/cm(2). The measured power conversion efficiency and differential quantum efficiency of the perovskite photonic crystal laser are 13.8 ± 0.8% and 35.8 ± 5.4%, respectively. Importantly, our approach enables scalability of the thin film lasers to a two-dimensional multielement pixelated array of microlasers which we demonstrate as a proof-of-concept for possible projection display applications. PMID:26997122

  6. High luminous flux from single crystal phosphor-converted laser-based white lighting system

    KAUST Repository

    Cantore, Michael

    2015-12-14

    The efficiency droop of light emitting diodes (LEDs) with increasing current density limits the amount of light emitted per wafer area. Since low current densities are required for high efficiency operation, many LED die are needed for high power white light illumination systems. In contrast, the carrier density of laser diodes (LDs) clamps at threshold, so the efficiency of LDs does not droop above threshold and high efficiencies can be achieved at very high current densities. The use of a high power blue GaN-based LD coupled with a single crystal Ce-doped yttrium aluminum garnet (YAG:Ce) sample was investigated for white light illumination applications. Under CW operation, a single phosphor-converted LD (pc-LD) die produced a peak luminous efficacy of 86.7 lm/W at 1.4 A and 4.24 V and a peak luminous flux of 1100 lm at 3.0 A and 4.85 V with a luminous efficacy of 75.6 lm/W. Simulations of a pc-LD confirm that the single crystal YAG:Ce sample did not experience thermal quenching at peak LD operating efficiency. These results show that a single pc-LD die is capable of emitting enough luminous flux for use in a high power white light illumination system.

  7. Superluminal media formed by photonic crystals for transformation optics-based invisibility cloaks

    Science.gov (United States)

    Semouchkina, Elena; Duan, Ran; Gandji, Navid P.; Jamilan, Saeid; Semouchkin, George; Pandey, Ravi

    2016-04-01

    We have developed an approach to building superluminal medium for transformation optics-based devices, including invisibility cloaks, from photonic crystals. Analysis of dispersion diagrams of 2D arrays composed from dielectric rods has shown that at frequencies corresponding to the second bands formed due to bandgap opening at increase of rod permittivity, the medium formed by arrays exhibits refractive indices providing for superluminal phase velocities of propagating waves. It is further demonstrated that rod arrays with various lattice constants could be used for realizing a range of superluminal index values prescribed by transformation optics for cylindrical cloaks at arbitrary chosen operating frequency. The performed studies allowed for solving a row of problems with employment rod arrays in the cloak medium: in particular, formulating transformation optics-based prescriptions for refractive index dispersion in the cloaking shell, defining the dimensions of array fragments capable of responding similar to infinite arrays, finding optimal distribution of linear arrays sets at their coiling to form concentric material layers in the cloaking shell, and employing interaction between neighboring array sets with various lattice constants to assist the realization of prescribed index dispersion. The performance of the superluminal medium formed by rod array sets was demonstrated on an example of a cloaking shell developed for microwave frequency range. In contrast to metamaterial-based cloak media, the developed media requires neither material homogenization, nor obtaining the effective parameters with peculiar values and Lorentz’s type resonances in rods. Combination of these advantages and low losses makes photonic crystals perspective materials for invisibility cloaks operating in THz and optical ranges.

  8. Compact and broadband waveguide taper based on partial bandgap photonic crystals

    Institute of Scientific and Technical Information of China (English)

    Jin Hou; Dingshan Gao; Huaming Wu; Zhiping Zhou

    2009-01-01

    Partial bandgap characteristics of parallelogram lattice photonic crystals are proposed to suppress the radiation modes in a compact dielectric waveguide taper so as to obtain high transmittance in a large wavelength range. Band structure of the photonic crystals shows that there exists a partial bandgap. The photonic crystals with partial bandgap are then used as the cladding of a waveguide taper to reduce the radiation loss efficiently. In comparison with the conventional dielectric taper and the complete bandgap photonic crystal taper, the partial bandgap photonic crystal taper has a high transmittance of above 85% with a wide band of 170 nm.

  9. Raman mapping for kinetic analysis of crystallization of amorphous drug based on distributional images.

    Science.gov (United States)

    Ueda, Hiroshi; Ida, Yasuo; Kadota, Kazunori; Tozuka, Yuichi

    2014-02-28

    The feasibility of Raman mapping for understanding the crystallization mechanism of an amorphous drug was investigated using described images. The crystallization tendency of amorphous indomethacin under dry condition at 30 °C was kinetically evaluated by means of Raman mapping and X-ray powder diffraction (XRPD) with change in the calculated crystallinities. Raman images directly revealed the occurrence of particle size-dependent non-uniform crystallization; slow crystallization of large particles, but fast crystallization of small particles. Kinetic analysis by fitting to the Kolmogorov-Johnson-Mehl-Avrami equation was performed for the crystallization profiles of both Raman mapping and XRPD data. For the Raman mapping data, the distribution of large particles was characterized and examined. The kinetic parameters calculated from the whole Raman image area agreed well with those of XRPD, suggesting accurate prediction of both techniques for the entire crystallization. Raman images revealed the change in the crystallization mechanism for the focused area; the large particles showed a reduced crystallization rate constant and an increase in the dimensional crystal growth exponent. Raman mapping is an attractive tool for quantitative and kinetic investigation of the crystallization mechanism with distributional images. PMID:24368105

  10. Nuclear magnetic resonance study of epoxy- based polymer-dispersed liquid crystal droplets

    CERN Document Server

    Han, J W

    1998-01-01

    In this work, polymer-dispersed liquid crystals (PDLC) samples were prepared and studied by nuclear magnetic resonance. Proton NMR spectra and spin-lattice relaxations of 4-cyano-4'-pentylbiphenyl(5CB) and p-methoxybenzylidene-p-n-butylaniline (MBBA) liquid crystals confined in microdroplets were measured. The experimental results were compared with those of the liquid crystals in the pores of silica-gels and with those of the mixing components. The experimental results indicated that the nematic ordering in the microdroplets differed markedly from that observed in bulk nematic crystals. In addition, we examined spin-lattice relaxation mechanisms. The proton spin-lattice relaxation mechanisms in bulk nematic liquid crystals are well established. However, when nematic liquid crystals are confined in microdroplets, the relaxation mechanisms are expected to be affected. We examined possible relaxation mechanisms to explain the observed increase in the spin-lattice relaxation rate of liquid crystals confined in m...

  11. Low cycle fatigue damage in nickel-base superalloy single crystals at elevated temperature

    Energy Technology Data Exchange (ETDEWEB)

    Fleury, E. (Centre des Materiaux P.M. Fourt, Ecole des Mines, 91 Evry (France)); Remy, L. (Centre des Materiaux P.M. Fourt, Ecole des Mines, 91 Evry (France))

    1993-08-15

    Low cycle fatigue tests on AM1 nickel-base superalloy single crystals were conducted under axial strain control at 650, 950 and 1100 C. The behaviour of the 001 orientation was investigated at the three temperatures, that of the 111, 101 and 213 specimens was studied at the two lower temperatures. The orientation dependence of fatigue life-total strain range curves was mainly due to variations in Young's modulus with orientation. Most cracks grow in stage II mode whatever the temperature. Cracks nucleate at micropores and in the interior of specimens at low temperatures; surface cracks induced by oxidation are dominant at high temperatures and low strain ranges. Most of fatigue life is spent in microcrack growth. (orig.)

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

    Science.gov (United States)

    Fleury, E.; Rémy, L.

    1994-12-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-01-01

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

  14. Direct fiber-coupled single photon source based on a photonic crystal waveguide

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Byeong-Hyeon, E-mail: seygene@kaist.ac.kr; Lee, Chang-Min; Lim, Hee-Jin [Department of Physics, KAIST, Daejeon 305-701 (Korea, Republic of); Schlereth, Thomas W.; Kamp, Martin [Technische Physik, Physikalisches Institut and Wilhelm Conrad Röntgen-Center for Complex Material Systems, Universität Würzburg, Am Hubland, D-97074 Würzburg (Germany); Höfling, Sven [Technische Physik, Physikalisches Institut and Wilhelm Conrad Röntgen-Center for Complex Material Systems, Universität Würzburg, Am Hubland, D-97074 Würzburg (Germany); SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews KY16 9SS (United Kingdom); Lee, Yong-Hee [Department of Physics, KAIST, Daejeon 305-701 (Korea, Republic of); Graduate School of Nanoscience and Technology (WCU), KAIST, Daejeon 305-701 (Korea, Republic of)

    2015-08-24

    A single photon source plays a key role in quantum applications such as quantum computers and quantum communications. Epitaxially grown quantum dots are one of the promising platforms to implement a good single photon source. However, it is challenging to realize an efficient single photon source based on semiconductor materials due to their high refractive index. Here we demonstrate a direct fiber coupled single photon source with high collection efficiency by employing a photonic crystal (PhC) waveguide and a tapered micro-fiber. To confirm the single photon nature, the second-order correlation function g{sup (2)}(τ) is measured with a Hanbury Brown-Twiss setup. The measured g{sup (2)}(0) value is 0.15, and we can estimate 24% direct collection efficiency from a quantum dot to the fiber.

  15. Light emitting devices based on Si nanoclusters: the integration with a photonic crystal and electroluminescence properties

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    We present the properties and potentialities of light emitting devices based on amorphous Si nanoclusters. Amorphous nanostructures may constitute an interesting alternative to Si nanocrystals for the monolithic integration of optical and electrical functions in Si technology. In fact, they exhibit an intense room temperature electroluminescence (EL). The EL properties of these devices have been studied as a function of current and of temperature. Moreover, to improve the extraction efficiency of the light, we have integrated the emitting system with a 2D photonic crystal structure opportunely fabricated by using conventional optical lithography to reduce the total internal reflection of the emitted light. The extraction efficiency in such devices increases by a factor of 4 at a resonance wavelength.

  16. Creep behaviour at 760 C of two nickel-based single crystal superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Diologent, F.; Caron, P. [ONERA, Chatillon (France)

    2003-07-01

    Creep tests have been performed at 760 C and 840 MPa on the AM1 and MC-NG nickel-based single crystal superalloys suited for gas turbine blade applications. The stress rupture life of MC-NG is slightly longer than that of AM1 but the creep behaviours of the two alloys are very different. Clear relationships have been established between the operative deformation mechanisms and the primary creep behaviours. Occurrence of these different deformation mechanisms is discussed by taking into account the effects of various parameters such as the Orowan stress, the {gamma}/{gamma}' lattice mismatch, the stacking fault energy and the solid solution strengthening of the {gamma} matrix. (orig.)

  17. A selectively coated photonic crystal fiber based surface plasmon resonance sensor

    DEFF Research Database (Denmark)

    Yu, X; Zhang, Y.; Pan, S.S.;

    2010-01-01

    We propose a novel design for a photonic crystal fiber based surface plasmonic resonance sensor. The sensor consists of selectively metal-coated air holes containing analyte channels, which enhance the phase matching between the plasmonic mode and the core-guided mode. Good refractive index...... sensitivity as high as 5500 nm/RIU (refractive index unit) can be achieved in the proposed structure. Compared with the entirely coated structure, the selectively coated sensor design demonstrates narrower resonance spectral width. Moreover, the greater resonance depth can improve the sensing performance...... in terms of signal to noise ratio (SNR). The improvements in spectral width and SNR can both contribute to a better detection limit for this refractive index sensor....

  18. Fabrication of Microcapsules for Dye-Doped Polymer-Dispersed Liquid Crystal-Based Smart Windows.

    Science.gov (United States)

    Kim, Mingyun; Park, Kyun Joo; Seok, Seunghwan; Ok, Jong Min; Jung, Hee-Tae; Choe, Jaehoon; Kim, Do Hyun

    2015-08-19

    A dye-doped polymer-dispersed liquid crystal (PDLC) is an attractive material for application in smart windows. Smart windows using a PDLC can be operated simply and have a high contrast ratio compared to those of other devices that employed photochromic or thermochromic material. However, in conventional dye-doped PDLC methods, dye contamination can cause problems and has a limited degree of commercialization of electric smart windows. Here, we report on an approach to resolve dye-related problems by encapsulating the dye in monodispersed capsules. By encapsulation, a fabricated dye-doped PDLC had a contrast ratio of >120 at 600 nm. This fabrication method of encapsulating the dye in a core-shell structured microcapsule in a dye-doped PDLC device provides a practical platform for dye-doped PDLC-based smart windows. PMID:26192469

  19. Biocompatible Single-Crystal Selenium Nanobelt Based Nanodevice as a Temperature-Tunable Photosensor

    Directory of Open Access Journals (Sweden)

    Yongshan Niu

    2012-01-01

    Full Text Available Selenium materials are widely used in photoelectrical devices, owing to their unique semiconductive properties. Single-crystal selenium nanobelts with large specific surface area, fine photoconductivity, and biocompatibility provide potential applications in biomedical nanodevices, such as implantable artificial retina and rapid photon detector/stimulator for optogenetics. Here, we present a selenium nanobelt based nanodevice, which is fabricated with single Se nanobelt. This device shows a rapid photo response, different sensitivities to visible light of variable wave length, and temperature-tunable property. The biocompatibility of the Se nanobelts was proved by MTT test using two cell lines. Our investigation introduced a photosensor that will be important for multiple potential applications in human visual system, photocells in energy or MEMS, and temperature-tunable photoelectrical device for optogenetics research.

  20. A novel polarization splitter based on three-core photonic crystal fibers

    Institute of Scientific and Technical Information of China (English)

    YANG Qian-qian; HOU Lan-tian

    2011-01-01

    @@ A novel polarization splitter based on photonic crystal fibers (PCFs) with three cores of high birefringence is proposed.The 45° linearly polarized light is launched into a core.After a coupling length (about 1500 μm), the x-and y-polarized light beams are separated into different cores.When the light is launched into another core, the x-and y-polarized light from different cores can be obtained and the degree of separation can be also adjusted.The polarization splitter is highly flexible and adjustable.The length of the polarization splitter is about 1500 μm which is just the coupling length.So it has appreciate significance of manufacturing mini-type photonic apparatus in integrated optics.

  1. SYNTHESIS AND PROPERTIES OF METAL COMPLEXES OF β-DIKETONE BASED SIDE CHAIN LIQUID CRYSTAL POLYSILOXANE

    Institute of Scientific and Technical Information of China (English)

    WU Fuzhou; ZHANG Rongben; JIANG Yingyan

    1991-01-01

    A new type of metal coordinated liquid crystalline polymers has been synthesized by complexation of metal ions with β-diketone based side chain liquid crystal polysiloxane (DKLCP).The complexation of copper ions with DKLCP greatly increases the phase transition temperature Tk from crystalline state to liquid crystalline state and Tcl from LC to isotropic state and makes the range of phase transition △T(△T= Tcl- Tk ) widened. These complexes are soluble in common organic solvents. However, the incorporation of europium ions into DKLCP molecules gives rise to reduction in liquid crystallinity and crosslinking in some cases. The DKLCP coordinated with suitable amount of Eu ions can show good liquid crystallinity and fluorescent property.

  2. Photonic crystal ring resonator based optical filters for photonic integrated circuits

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, S., E-mail: mail2robinson@gmail.com [Department of Electronics and Communication Engineering, Mount Zion College of Engineering and Technology, Pudukkottai-622507, Tamil Nadu (India)

    2014-10-15

    In this paper, a two Dimensional (2D) Photonic Crystal Ring Resonator (PCRR) based optical Filters namely Add Drop Filter, Bandpass Filter, and Bandstop Filter are designed for Photonic Integrated Circuits (PICs). The normalized output response of the filters is obtained using 2D Finite Difference Time Domain (FDTD) method and the band diagram of periodic and non-periodic structure is attained by Plane Wave Expansion (PWE) method. The size of the device is minimized from a scale of few tens of millimeters to the order of micrometers. The overall size of the filters is around 11.4 μm × 11.4 μm which is highly suitable of photonic integrated circuits.

  3. Direct fiber-coupled single photon source based on a photonic crystal waveguide

    International Nuclear Information System (INIS)

    A single photon source plays a key role in quantum applications such as quantum computers and quantum communications. Epitaxially grown quantum dots are one of the promising platforms to implement a good single photon source. However, it is challenging to realize an efficient single photon source based on semiconductor materials due to their high refractive index. Here we demonstrate a direct fiber coupled single photon source with high collection efficiency by employing a photonic crystal (PhC) waveguide and a tapered micro-fiber. To confirm the single photon nature, the second-order correlation function g(2)(τ) is measured with a Hanbury Brown-Twiss setup. The measured g(2)(0) value is 0.15, and we can estimate 24% direct collection efficiency from a quantum dot to the fiber

  4. Effects of copper-based alloy on the synthesis of single-crystal diamond

    CERN Document Server

    Chen Li Xue; Ma Hong An; Jia Xiao Peng; Wakatsuki, M; Zou Guang Tian

    2002-01-01

    The catalytic effects of copper-based alloys in diamond growth have been investigated. A single crystal of diamond has been obtained by the temperature gradient method (TGM), using Cu-Mn-Co and Cu-Co alloys as catalysts. It was found that the melted Cu-Mn-Co and Cu-Co alloys show low viscosity. The eutectic temperatures of these two alloys with graphite were between 1130 and 1150 deg. C, and the temperature of the transition to diamond was over 1300 deg. C at 5.5 GPa. High-quality diamond could not be obtained in Cu-Co alloy by the TGM. Our results suggest that adding Cu to a catalyst cannot decrease the reaction temperature for diamond growth.

  5. Ultrabroadband, Midinfrared Supercontinuum Generation in Dispersion Engineered As2Se3-Based Chalcogenide Photonic Crystal Fibers

    Directory of Open Access Journals (Sweden)

    Rim Cherif

    2013-01-01

    Full Text Available Small core As2Se3-based photonic crystal fibers (PCFs are accurately characterized for compact, high power, ultrabroadband, and coherent supercontinuum generation within few millimeters fiber length. Bandwidths of ~5.3 μm, 5 μm, and 3.2 μm were calculated for hole-to-hole spacings Λ= 3.5 μm, 4.5 μm, and 5.5 μm, respectively. The spectral broadening in the chalcogenide PCF is mainly caused by self-phase modulation and Raman-induced soliton self-frequency shift. The results show that small core As2Se3 PCFs are a promising candidate for mid-IR SCG up to ~8 μm.

  6. High-sensitivity refractive index sensors based on fused tapered photonic crystal fiber

    Science.gov (United States)

    Fu, Xing-hu; Xie, Hai-yang; Yang, Chuan-qing; Qu, Yu-wei; Zhang, Shun-yang; Fu, Guang-wei; Guo, Xuan; Bi, Wei-hong

    2016-05-01

    In this paper, a novel liquid refractive index (RI) sensor based on fused tapered photonic crystal fiber (PCF) is proposed. It is fabricated by fusing and tapering a section of PCF which is spliced with two single-mode fibers (SMFs). Due to the fused biconical taper method, the sensor becomes longer and thinner, to make the change of the outside RI has more direct effects on the internal optical field of the PCF, which finally enhances the sensitivity of this sensor. Experimental results show that the transmission spectra of the sensor are red-shifted obviously with the increase of RI. The longer the tapered region of the sensor, the higher the sensitivity is. This sensor has the advantages of simple structure, easy fabrication, high performance and so on, so it has potential applications in RI measurement.

  7. A superhigh-frequency optoelectromechanical system based on a slotted photonic crystal cavity

    CERN Document Server

    Sun, Xiankai; Poot, Menno; Xiong, Chi; Tang, Hong X

    2012-01-01

    We develop an all-integrated optoelectromechanical system that operates in the superhigh frequency band. This system is based on an ultrahigh-Q slotted photonic crystal (PhC) nanocavity formed by two PhC membranes, one of which is patterned with electrode and capacitively driven. The strong simultaneous electromechanical and optomechanical interactions yield efficient electrical excitation and sensitive optical transduction of the bulk acoustic modes of the PhC membrane. These modes are identified up to a frequency of 4.20 GHz, with their mechanical Q factors ranging from 240 to 1,730. Directly linking signals in microwave and optical domains, such optoelectromechanical systems will find applications in microwave photonics in addition to those that utilize the electromechanical and optomechanical interactions separately.

  8. Compact beam splitters based on self-imaging phenomena in one-dimensional photonic crystal waveguides

    Institute of Scientific and Technical Information of China (English)

    Bing Chen; Lin Huang; Yongdong Li; Chunliang Liu; Guizhong Liu

    2012-01-01

    A fundamental 1 ×2 beam splitter based on the self-imaging phenomena in multi-mode one-dimensional (1D) photonic crystal (PC) waveguides is presented,and its transmission characteristics are investigated using the finite-difference time-domain method.Calculated results indicate that a high transmittance (>95%) can be observed within a wide frequency band for the 1×2 beam splitter without complicated structural optimizations.In this letter,a simple and compact 1 ×4 beam splitter is constructed by combining the fundamental 1 ×2 beam splitter with the flexible bends of 1D PC waveguides.Such beam splitters can be applied to highly dense photonic integrated circuits.

  9. Analysis of a highly birefringent asymmetric photonic crystal fibre based on a surface plasmon resonance sensor

    Science.gov (United States)

    Liu, Chao; Wang, Famei; Zheng, Shijie; Sun, Tao; Lv, Jingwei; Liu, Qiang; Yang, Lin; Mu, Haiwei; Chu, Paul K.

    2016-07-01

    A highly birefringent photonic crystal fibre is proposed and characterized based on a surface plasmon resonance sensor. The birefringence of the sensor is numerically analyzed by the finite-element method. In the numerical simulation, the resonance wavelength can be directly positioned at this birefringence abrupt change point and the depth of the abrupt change of birefringence reflects the intensity of excited surface plasmon. Consequently, the novel approach can accurately locate the resonance peak of the system without analyzing the loss spectrum. Simulated average sensitivity is as high as 1131 nm/RIU, corresponding to a resolution of 1 × 10-4 RIU in this sensor. Therefore, results obtained via the approach not only show polarization independence and less noble metal consumption, but also reveal better performance in terms of accuracy and computation efficiency.

  10. High efficiency all-optical diode based on photonic crystal waveguide

    Science.gov (United States)

    Liu, Bin; Liu, Yun-Feng; Li, Shu-Jing; He, Xing-Dao

    2016-06-01

    A high efficiency all-optical diode based on photonic crystal (PC) waveguide has been proposed and numerically investigated by finite-difference time-domain (FDTD) method. The structure is asymmetrically coupled by a Fano cavity containing nonlinear Kerr medium and a F-P cavity in PC waveguide. Because of interference between two cavities, Fano peak and F-P peak can both appear in transmission spectra. Working wavelength is set between the two peaks and approaching to Fano peak. For forward launch with suitable light intensity, nonlinear Kerr effect of micro-cavity can be excited. It would result in red shift of Fano peak and achieving forward transmission. But due to the asymmetric design, backward launch need stronger incidence light to excite Kerr effect. This design has many advantages, including high maximum transmittance (>90%), high transmittance contrast ratio, low power threshold, short response time (picosecond level), ease of integration.

  11. Fluorescence-based remote irradiation sensor in liquid-filled hollow-core photonic crystal fiber

    Science.gov (United States)

    Zeltner, R.; Bykov, D. S.; Xie, S.; Euser, T. G.; Russell, P. St. J.

    2016-06-01

    We report an irradiation sensor based on a fluorescent "flying particle" that is optically trapped and propelled inside the core of a water-filled hollow-core photonic crystal fiber. When the moving particle passes through an irradiated region, its emitted fluorescence is captured by guided modes of the fiber core and so can be monitored using a filtered photodiode placed at the fiber end. The particle speed and position can be precisely monitored using in-fiber Doppler velocimetry, allowing the irradiation profile to be measured to a spatial resolution of ˜10 μm. The spectral response can be readily adjusted by appropriate choice of particle material. Using dye-doped polystyrene particles, we demonstrate detection of green (532 nm) and ultraviolet (340 nm) light.

  12. Intensified crystallization in complex media: heuristics for crystallization of platform chemicals

    NARCIS (Netherlands)

    Urbanus, J.; Roelands, C.P.M.; Verdoes, D.; Horst, J.H. ter

    2012-01-01

    This paper presents heuristics for the integration of fermentation with the appropriate crystallization based in-situ product recovery (ISPR) technique. Here techniques, such as co-crystallization (CC), evaporative crystallization (EC), template induced crystallization (TIC), cooling crystallization

  13. Position algorithm for monolithic scintillation crystals based on charge projection readout

    Science.gov (United States)

    Pani, R.; Bettiol, M.; Preziosi, E.; Cinti, M. N.; Borrazzo, C.; Pellegrini, R.; Di Castro, E.; Fabbri, A.

    2016-01-01

    Nuclear medicine imaging devices commonly use multi-element photo detection systems, composed of an array of N × N elements, each one providing an individual signal. Many strategies have been developed to reduce the number of readout channels, one of the main approaches is the Rows and Columns (R/C) projection logic. In this paper we proposed a modified version of Raised To the Power (RTP) algorithm adapted to R/C logic. In order to validate its efficiency a linear scanning irradiation on two 49× 49 mm2 LaBr3:Ce (0.5%) crystals with different thickness (4 mm and 10 mm) was carried out. Imaging performance analysis was made in terms of position linearity, Field-of-View (FoV) enlargement and spatial resolution. Imaging results from Anger Logic, RTP algorithm based on single element readout and RTP algorithm based on R/C readout were compared. A notable advantage of using RTP algorithms instead of Anger Logic was found: the FoV widens from about 30% to more than 70% of the detector area whereas the spatial resolution is highly improved, especially for off-center interactions, both for 4 mm-thick and 10 mm-thick crystals. Furthermore, imaging performance with the R/C readout is just slightly different from the single element one (FoV reduction less than 7% and SR worsening less than 10%). The R/C adapted RTP algorithm opens doors to high imaging performance with a substantial reduction of complexity and cost in the readout electronics.

  14. Controlling the Vaterite CaCO3 Crystal Pores. Design of Tailor-Made Polymer Based Microcapsules by Hard Templating.

    Science.gov (United States)

    Feoktistova, Natalia; Rose, Juergen; Prokopović, Vladimir Z; Vikulina, Anna S; Skirtach, Andre; Volodkin, Dmitry

    2016-05-01

    The spherical vaterite CaCO3 microcrystals are nowadays widely used as sacrificial templates for fabrication of various microcarriers made of biopolymers (e.g., proteins, nucleic acids, enzymes) due to porous structure and mild template elimination conditions. Here, we demonstrated for the first time that polymer microcarriers with tuned internal nanoarchitecture can be designed by employing the CaCO3 crystals of controlled porosity. The layer-by-layer deposition has been utilized to assemble shell-like (hollow) and matrix-like (filled) polymer capsules due to restricted and free polymer diffusion through the crystal pores, respectively. The crystal pore size in the range of few tens of nanometers can be adjusted without any additives by variation of the crystal preparation temperature in the range 7-45 °C. The temperature-mediated growth mechanism is explained by the Ostwald ripening of nanocrystallites forming the crystal secondary structure. Various techniques including SEM, AFM, CLSM, Raman microscopy, nitrogen adsorption-desorption, and XRD have been employed for crystal and microcapsule analysis. A three-dimensional model is introduced to describe the crystal internal structure and predict the pore cutoff and available surface for the pore diffusing molecules. Inherent biocompatibility of CaCO3 and a possibility to scale the porosity in the size range of typical biomacromolecules make the CaCO3 crystals extremely attractive tools for template assisted designing tailor-made biopolymer-based architectures in 2D to 3D targeted at drug delivery and other bioapplications. PMID:27052835

  15. Mechanical modeling of cholesterol crystallization in atherosclerotic plaques base on Micro-OCT images (Conference Presentation)

    Science.gov (United States)

    Luo, Yuemei; Liu, Xinyu; Chen, Si; Cui, Dongyao; Wang, Xianghong; Liu, Linbo

    2016-02-01

    Plaque rupture is the critical cause of cardiovascular thrombosis but this process is still under discussion. Recent studies show that, during crystallization, cholesterol crystals in atheromatous plaques accumulate rapidly in a limited space and may result in plaque rupture. However, the actual role of cholesterol crystals on plaque rupture remains unclear due to the lack of detailed morphological information of cholesterol crystals. In this study, we used a Micro-optical coherence tomography (µOCT) setup with 1-2 µm spatial resolution to extract the geometry of cholesterol crystals from human atherosclerotic artery ex vivo firstly. With measured dimensions of cholesterol crystals by this µOCT system (the average length and thickness of 269.1±80.16 µm and 3.0±0.33 µm), we developed a two-dimensional mechanical model in which rectangular shaped cholesterol crystals distribute at different locations spatially. We predicted the stress on the thin cap induced by the expansion of cholesterol crystals by use of finite-element method. Since a large portion of plaques (58%) rupture at points of peak circumferential stress (PCS), we used PCS as the primary indicator of plaque stability with blood pressure of 14.6 kPa on the lumen. The results demonstrate that loading of the concentrated crystals especially at the cap shoulder destabilize the plaque by proportionally increasing the PCS, while evenly distributed crystals loading along the cap might impose less PCS to the plaque than the concentrated case.

  16. Enabling structure-based drug design of Tyk2 through co-crystallization with a stabilizing aminoindazole inhibitor

    Directory of Open Access Journals (Sweden)

    Argiriadi Maria A

    2012-09-01

    Full Text Available Abstract Background Structure-based drug design (SBDD can accelerate inhibitor lead design and optimization, and efficient methods including protein purification, characterization, crystallization, and high-resolution diffraction are all needed for rapid, iterative structure determination. Janus kinases are important targets that are amenable to structure-based drug design. Here we present the first mouse Tyk2 crystal structures, which are complexed to 3-aminoindazole compounds. Results A comprehensive construct design effort included N- and C-terminal variations, kinase-inactive mutations, and multiple species orthologs. High-throughput cloning and expression methods were coupled with an abbreviated purification protocol to optimize protein solubility and stability. In total, 50 Tyk2 constructs were generated. Many displayed poor expression, inadequate solubility, or incomplete affinity tag processing. One kinase-inactive murine Tyk2 construct, complexed with an ATP-competitive 3-aminoindazole inhibitor, provided crystals that diffracted to 2.5–2.6 Å resolution. This structure revealed initial “hot-spot” regions for SBDD, and provided a robust platform for ligand soaking experiments. Compared to previously reported human Tyk2 inhibitor crystal structures (Chrencik et al. (2010 J Mol Biol 400:413, our structures revealed a key difference in the glycine-rich loop conformation that is induced by the inhibitor. Ligand binding also conferred resistance to proteolytic degradation by thermolysin. As crystals could not be obtained with the unliganded enzyme, this enhanced stability is likely important for successful crystallization and inhibitor soaking methods. Conclusions Practical criteria for construct performance and prioritization, the optimization of purification protocols to enhance protein yields and stability, and use of high-throughput construct exploration enable structure determination methods early in the drug discovery process

  17. SHG Materials Based on the AlPO4-5 Single Crystals

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Large AlPO4-5 molecular sieve single crystals with high optical quality were synthesized hydrothermally by using TPA as template. As-synthesized crystals were calcined under O2 atmosphere to remove the organic templates in the channels. Disperse-Red-1 (DR1) and p-nitroaniline (pNA) molecules have been successfully incorporated into the one-dimensional channels of AlPO4-5 single crystals respectively by means of vapor phase diffusion. XRD patterns reveal that the loading of organic molecules has not destroyed the structures of AlPO4-5 crystals. Polarizing microscope and SHG results indicate that the DR1 and pNA molecules are well aligned in a preferred direction along the crystal channels. The different polarization-dependence SH intensity shows that different SHG processes occur in the DR1- and pNA-loaded AlPO4-5 crystals.

  18. Development of a task-based design approach for solution crystallization processes

    OpenAIRE

    Lakerveld, R.

    2010-01-01

    Crystallization is historically one of the most important separation and product formation technologies in chemical industry. The future impact of crystallization is expected to increase as new high-added value products are often in crystalline form and need to comply with increasingly stringent product quality requirements. This calls for better designs and performance of new crystallization units in chemical processes. A key challenge is to improve in the design phase the control over the p...

  19. Security devices based on liquid crystals doped with a colour dye

    OpenAIRE

    Carrasco Vela, Carlos; Quintana Arregui, Patxi Xabier; Otón, E.; Geday, Morten Andreas; Otón Sánchez, José Manuel

    2011-01-01

    Liquid crystal properties make them useful for the development of security devices in applications of authentication and detection of fakes. Induced orientation of liquid crystal molecules and birefringence are the two main properties used in security devices. Employing liquid crystal and dichroic colorants, we have developed devices that show, with the aid of a polarizer, multiple images on each side of the device. Rubbed polyimide is used as alignment layer on each substrate of the LC ce...

  20. Performance of VATA64HDR16 ASIC for medical physics applications based on continuous crystals and SiPMs

    International Nuclear Information System (INIS)

    Detectors based on Silicon Photomultipliers (SiPMs) coupled to continuous crystals are being tested in medical physics applications due to their potential high resolution and sensitivity. To cope with the high granularity required for a very good spatial resolution, SiPM matrices with a large amount of elements are needed. To be able to read the information coming from each individual channel, dedicated ASICs are employed. The VATA64HDR16 ASIC is a 64-channel, charge-sensitive amplifier that converts the collected charge into a proportional current or voltage signal. A complete assessment of the suitability of that ASIC for medical physics applications based on continuous crystals and SiPMs has been carried out. The input charge range is linear from 0−2 pC up to 55 pC. The energy resolution obtained at 511 keV is 10% FWHM with a LaBr3 crystal and 16% FWHM with a LYSO crystal. A coincidence timing resolution of 24 ns FWHM is obtained with two LYSO crystals

  1. Hydrostatic Parameters and Domain Effects in Novel 2-2 Composites Based on PZN-0.12PT Single Crystals

    Directory of Open Access Journals (Sweden)

    Vitaly Yu. Topolov

    2011-01-01

    Full Text Available A novel 0.88Pb(Zn1/3Nb2/3O3-0.12PbTiO3 crystal/polymer composite with 2-2 connectivity is studied at variable orientations of spontaneous polarisation vector of the crystal component. Orientation and volume-fraction dependences of the hydrostatic piezoelectric coefficients dh*, eh*, and gh* and hydrostatic electromechanical coupling factor kh* are related to the important role of the piezoelectric and elastic anisotropy of single-domain layers of the 2-2 composite. The record value of |eh∗|≈77 C/m2 near the absolute-minimum point and the correlation between the hydrostatic (eh* and piezoelectric (e3j* coefficients and between the hydrostatic (gh* and piezoelectric (g3j* coefficients are first established. This discovery is of value for hydrostatic and piezotechnical applications. The hydrostatic performance of the composite based on the single-domain 0.88Pb(Zn1/3Nb2/3O3-0.12PbTiO3 crystal is compared to the performance of the 2–2 composites based on either the same polydomain crystal or the related single-domain crystal.

  2. A super narrow band filter based on silicon 2D photonic crystal resonator and reflectors

    Science.gov (United States)

    Wang, Yuanyuan; Chen, Deyuan; Zhang, Gang; Wang, Juebin; Tao, Shangbin

    2016-03-01

    In this paper, a novel structure of super narrow band filter based on two-dimensional square lattice photonic crystals of silicon rods in air for 1.5 um communication is proposed and studied. COMSOL Multiphysics4.3b software is used to simulate the optical behavior of the filter. The filter consists of one point-defect-based resonator and two line-defect-based reflectors. The resonance frequency, transmission coefficient and quality factor are investigated by varying the parameters of the structure. In design, a silicon rod is removed to form the resonator; for the rows of rods above and below the resonator, a part of the rods are removed to form the reflectors. By optimizing the parameters of the filter, the quality factor and transmission coefficient of the filter at the resonance frequency of 2e14 Hz can reach 1330 and 0.953, respectively. The super narrow band filter can be integrated into optical circuit for its micron size. Also, it can be used for wavelength selection and noise filtering of optical amplifier in future communication application.

  3. Apparatus for detecting and recognizing analytes based on their crystallization patterns

    Science.gov (United States)

    Morozov, Victor; Bailey, Charles L.; Vsevolodov, Nikolai N.; Elliott, Adam

    2010-12-14

    The invention contemplates apparatuses for recognition of proteins and other biological molecules by imaging morphology, size and distribution of crystalline and amorphous dry residues in droplets (further referred to as "crystallization patterns") containing predetermined amount of certain crystal-forming organic compounds (reporters) to which protein to be analyzed is added. Changes in the crystallization patterns of a number of amino-acids can be used as a "signature" of a protein added. Also, changes in the crystallization patterns, as well as the character of such changes, can be used as recognition elements in analysis of protein molecules.

  4. High resolution detectors based on continuous crystals and SiPMs for small animal PET

    Energy Technology Data Exchange (ETDEWEB)

    Cabello, J. [Instituto de Física Corpuscular, Universitat de València/CSIC, Valencia (Spain); Barrillon, P. [Laboratoire de L' Accélérateur Linéaire (LAL), Orsay (France); Barrio, J. [Instituto de Física Corpuscular, Universitat de València/CSIC, Valencia (Spain); Bisogni, M.G.; Del Guerra, A. [Dipartimento di Fisica “E. Fermi“, Università di Pisa and INFN Pisa, Pisa (Italy); Lacasta, C. [Instituto de Física Corpuscular, Universitat de València/CSIC, Valencia (Spain); Rafecas, M. [Instituto de Física Corpuscular, Universitat de València/CSIC, Valencia (Spain); Departamento de Física Atómica, Nuclear y Molecular, Universitat de València, Valencia (Spain); Saikouk, H. [Laboratoire de Physique Nucléaire, Faculté des Sciences, Université Mohammed V-Agdal, Rabat (Morocco); Solaz, C.; Solevi, P. [Instituto de Física Corpuscular, Universitat de València/CSIC, Valencia (Spain); La Taille, C. de [Laboratoire de L' Accélérateur Linéaire (LAL), Orsay (France); Llosá, G., E-mail: gabriela.llosa@ific.uv.es [Instituto de Física Corpuscular, Universitat de València/CSIC, Valencia (Spain)

    2013-08-01

    Sensitivity and spatial resolution are the two main factors to maximize in emission imaging. The improvement of one factor deteriorates the other with pixelated crystals. In this work we combine SiPM matrices with monolithic crystals, using an accurate γ-ray interaction position determination algorithm that provides depth of interaction. Continuous crystals provide higher sensitivity than pixelated crystals, while an accurate interaction position determination does not degrade the spatial resolution. Monte Carlo simulations and experimental data show good agreement both demonstrating sub-millimetre intrinsic spatial resolution. A system consisting in two rotating detectors in coincidence is currently under operation already producing tomographic images.

  5. Low temperature y-ray spectrometers based on bulk superconducting and dielectric absorber crystals

    Energy Technology Data Exchange (ETDEWEB)

    Netel, H

    1999-11-19

    Many areas of research rely on the detection of radiation, in the form of single photons or particles. By measuring the photons or particles coming from an object a lot can be learned about the object under study. In some cases there is a simple need to know the number of photons coming from the source. In cases like this a simple counter, like a Geiger-Mueller survey meter, will suffice. In other cases one want to know the spectral distribution of the photons coming from the source. In cases like that a spectrometer is needed that can distinguish between photons with different energies, like a diffraction or transmission grating. The work presented in this thesis focused on the development of a new generation broad band spectrometer that has a high energy resolving power, combined with a high absorption efficiency for photon energies above 10 keV and up to 500 keV. The spectrometers we are developing are based on low-temperature sensors, like superconducting tunnel junctions or transition edge sensors, that are coupled to bulk absorber crystals. We use the low-temperature sensors because they can offer a significant improvement in energy resolving power, compared to conventional spectrometers. We couple the low-temperature sensors to bulk absorber crystals to increase the absorption efficiency. In this chapter I introduce different types of radiation detectors and spectrometers and areas where they are being used. I also discuss the history and motivation of low-temperature spectrometers and show some of the impressive results that have been achieved in this field over the last few years. Finally I discuss the outline of this thesis.

  6. Colloidal crystal based plasma polymer patterning to control Pseudomonas aeruginosa attachment to surfaces.

    Science.gov (United States)

    Pingle, Hitesh; Wang, Peng-Yuan; Thissen, Helmut; McArthur, Sally; Kingshott, Peter

    2015-01-01

    Biofilm formation on medical implants and subsequent infections are a global problem. A great deal of effort has focused on developing chemical contrasts based on micro- and nanopatterning for studying and controlling cells and bacteria at surfaces. It has been known that micro- and nanopatterns on surfaces can influence biomolecule adsorption, and subsequent cell and bacterial adhesion. However, less focus has been on precisely controlling patterns to study the initial bacterial attachment mechanisms and subsequently how the patterning influences the role played by biomolecular adsorption on biofilm formation. In this work, the authors have used colloidal self-assembly in a confined area to pattern surfaces with colloidal crystals and used them as masks during allylamine plasma polymer (AAMpp) deposition to generate highly ordered patterns from the micro- to the nanoscale. Polyethylene glycol (PEG)-aldehyde was grafted to the plasma regions via "cloud point" grafting to prevent the attachment of bacteria on the plasma patterned surface regions, thereby controlling the adhesive sites by choice of the colloidal crystal morphology. Pseudomonas aeruginosa was chosen to study the bacterial interactions with these chemically patterned surfaces. Scanning electron microscope, x-ray photoelectron spectroscopy (XPS), atomic force microscopy, and epifluorescence microscopy were used for pattern characterization, surface chemical analysis, and imaging of attached bacteria. The AAMpp influenced bacterial attachment because of the amine groups displaying a positive charge. XPS results confirm the successful grafting of PEG on the AAMpp surfaces. The results showed that PEG patterns can be used as a surface for bacterial patterning including investigating the role of biomolecular patterning on bacterial attachment. These types of patterns are easy to fabricate and could be useful in further applications in biomedical research. PMID:26634448

  7. 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;

    2011-01-01

    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...

  8. High-performance slow light photonic crystal waveguides with topology optimized or circular-hole based material layouts

    DEFF Research Database (Denmark)

    Wang, Fengwen; Jensen, Jakob Søndergaard; Sigmund, Ole

    2012-01-01

    Photonic crystal waveguides are optimized for modal confinement and loss related to slow light with high group index. A detailed comparison between optimized circular-hole based waveguides and optimized waveguides with free topology is performed. Design robustness with respect to manufacturing im...

  9. The Second Order Guided Modes Based on Photonic Bandgap Effects in Air/Glass Photonic Crystal Fibers

    Institute of Scientific and Technical Information of China (English)

    YAO Lei; LOU Shu-Qin; JIAN Shui-Sheng

    2009-01-01

    We introduce a defect site in the periodic structure of a photonic bandgap fiber,to confine and guide the second order mode by photonic bandgap effects.Based on a high air-filling fraction photonic crystal cladding structure,a simplified model with an equivalent air cladding was proposed to explore and analyze the properties of this second order guided mode.

  10. Periodic order and defects in Ni-based inverse opal-like crystals on the mesoscopic and atomic scale

    NARCIS (Netherlands)

    Chumakova, A. V.; Valkovskiy, G. A.; Mistonov, A. A.; Dyadkin, V. A.; Grigoryeva, N. A.; Sapoletova, N. A.; Napolskii, K. S.; Eliseev, A. A.; Petukhov, Andrei V.; Grigoriev, S. V.

    2014-01-01

    The structure of inverse opal crystals based on nickel was probed on the mesoscopic and atomic levels by a set of complementary techniques such as scanning electron microscopy and synchrotron microradian and wide-angle diffraction. The microradian diffraction revealed the mesoscopic-scale face-cente

  11. Crystallization behavior of Fe- and Co-based bulk metallic glasses and their glass-forming ability

    Energy Technology Data Exchange (ETDEWEB)

    Louzguine-Luzgin, D.V., E-mail: dml@wpi-aimr.tohoku.ac.jp [WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Bazlov, A.I. [WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); National University of Science and Technology “MISiS”, Moscow 119049 (Russian Federation); Ketov, S.V. [WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Inoue, A. [International Institute of Green Materials, Josai International University, Togane 283-8555 (Japan); School of Materials Science and Engineering, Tianjin University, 300072 (China); Department of Physics, King Abdulaziz University, Jeddah 22254 (Saudi Arabia)

    2015-07-15

    In the present work we study and compare the crystallization behavior of Fe- and Co-based good bulk glass formers with an exceptionally high glass-forming ability leading to the critical thickness of cast samples reaching 1 cm. For Fe-based alloys we also investigate the effect of opposite C/B content ratio on the glass-forming ability and the crystallization behavior. The structure and phase composition of the glassy samples were examined by conventional X-ray diffractometry and transmission electron microscopy while thermal stability and phase transformations were studied by differential scanning calorimetry. The reasons for high glass-forming ability are discussed. The glass-forming ability of the studied alloys depends on both factors: the type of crystallization reaction and characteristic temperatures. - Highlights: • Crystallization of Fe-based and Co-based bulk glass-forming alloys. • The reasons for enhanced glass-forming ability of these alloys are discussed. • Low growth rate of χ-Fe{sub 36}Cr{sub 12}Mo{sub 10} phase. • Reduced liquidus temperature of Fe{sub 48}Cr{sub 15}Mo{sub 14}C{sub 6}B{sub 15}RE{sub 2} alloys.

  12. Short-wavelength two-photon excitation fluorescence microscopy of tryptophan with a photonic crystal fiber based light source

    NARCIS (Netherlands)

    J.A. Palero (Jonathan); V.O. Boer (Vincent); J.C. Vijverberg (Jacob); H.C. Gerritsen (Hans); H.J.C.M. Sterenborg (Dick)

    2005-01-01

    textabstractWe report on a novel and simple light source for short-wavelength two-photon excitation fluorescence microscopy based on the visible nonsolitonic radiation from a photonic crystal fiber. We demonstrate tunability of the light source by varying the wavelength and intensity of the Ti:Sapph

  13. Synthesis, crystal structure and thermodynamic properties of a new praseodymium Schiff-base complex

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chuan-Hua, E-mail: lichuanhua0526@126.com [School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, Hunan (China); Hunan Provincial Key Laboratory of Xiangnan Rare-Precious Metals Compounds and Applications, Department of Chemistry and Life Science, Xiangnan University, Chenzhou 423000, Hunan (China); Song, Xiang-Zhi, E-mail: xzsong@csu.edu.cn [School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, Hunan (China); Jiang, Jian-Hong [Hunan Provincial Key Laboratory of Xiangnan Rare-Precious Metals Compounds and Applications, Department of Chemistry and Life Science, Xiangnan University, Chenzhou 423000, Hunan (China); Gu, Hui-Wen [State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, Hunan (China); Tao, Li-Ming; Yang, Ping; Li, Xu; Xiao, Sheng-Xiong; Yao, Fei-Hong; Liu, Wen-Qi; Xie, Jin-Qi; Peng, Meng-Na; Pan, Lan; Wu, Xi-Bin; Jiang, Chao; Wang, Song; Xu, Man-Fen [Hunan Provincial Key Laboratory of Xiangnan Rare-Precious Metals Compounds and Applications, Department of Chemistry and Life Science, Xiangnan University, Chenzhou 423000, Hunan (China); Li, Qiang-Guo, E-mail: liqiangguo@163.com [Hunan Provincial Key Laboratory of Xiangnan Rare-Precious Metals Compounds and Applications, Department of Chemistry and Life Science, Xiangnan University, Chenzhou 423000, Hunan (China)

    2014-04-01

    Highlights: • A new mononuclear Schiff base praseodymium complex was synthesized. • Based on Hess's law, thermochemical cycles of two reactions were designed. • The dissolution enthalpies were measured by a solution–reaction calorimeter. • The standard molar enthalpy of formation of the complex was calculated. - Abstract: The title complex [Pr(H{sub 2}vanen)(NO{sub 3}){sub 2}(H{sub 2}O){sub 2}·NO{sub 3}] was synthesized reacting of Valen Schiff-base ligand [H{sub 2}vanen = N,N′-ethylene-bis(3-methoxysalicylideneimine)] and Pr(NO{sub 3}){sub 3}·6H{sub 2}O in ethanol at 60 °C. The complex was crystallized in the monoclinic crystal system with space group P21/c. The coordination polyhedron of Pr(III) ion was consisted of two bidentate nitrate ions, two molecules of water and one ligand which coordinated through oxygen atoms of the two phenolic and methoxy groups. After designing two reasonable thermochemical cycles according to Hess's law, the calorimetric experiments were conducted using isoperibol solution–reaction calorimeter at a constant temperature of 298.15 K. The standard molar enthalpy changes of two reactions were determined to be Δ{sub r}H{sub m}{sup θ}(1a)=−(51.94±1.26) kJ mol{sup −1} and Δ{sub r}H{sub m}{sup θ}(1b)=−(8.62±1.34) kJ mol{sup −1}. Then the standard molar enthalpies of formation of the ligand and the title complex were calculated to be Δ{sub f}H{sub m}{sup θ} [H{sub 2}vanen(s), 298.15 K] = −(517.75 ± 2.36) kJ mol{sup −1} and Δ{sub f}H{sub m}{sup θ} [Pr(H{sub 2}vanen)(NO{sub 3}){sub 2}(H{sub 2}O){sub 2}·NO{sub 3} (s), 298.15 K] = −(2454.8 ± 2.7) kJ mol{sup −1}, respectively. The rationality of two thermochemical cycles was verified by UV spectra and refractive indexes.

  14. New method for computation of band structures in 1D photonic crystals based on the Fresnel equations

    Science.gov (United States)

    Roshan Entezar, S.

    2013-02-01

    In this paper, we present a new method for calculation of band structure in one-dimensional bilayer photonic crystals, based on the Fresnel equations. We derive a new relation to obtain the band structure without using the Floquet theorem. It is shown that this relation can be simplified under the assumption that the single-path phase-shift acquired through the individual layers of the photonic crystal be equal to ? . The results obtained by our method are compared with the ones obtained from the transfer matrix method to show that they are exactly identical.

  15. Tunable microwave bandpass filter integrated power divider based on the high anisotropy electro-optic nematic liquid crystal

    Science.gov (United States)

    Liu, Yupeng; Liu, Yang; Li, Haiyan; Jiang, Di; Cao, Weiping; Chen, Hui; Xia, Lei; Xu, Ruimin

    2016-07-01

    A novel, compact microwave tunable bandpass filter integrated power divider, based on the high anisotropy electro-optic nematic liquid crystal, is proposed in this letter. Liquid crystal, as the electro-optic material, is placed between top inverted microstrip line and the metal plate. The proposed structure can realize continuous tunable bandpass response and miniaturization. The proposed design concept is validated by the good performance of simulation results and experimental results. The electro-optic material has shown great potential for microwave application.

  16. Experimental demonstration of broadband femtosecond optical parametric amplification based on YCOB crystal at near critical wavelength degeneracy

    Science.gov (United States)

    Guo, Xiaoyang; Leng, Yuxin; Li, Yanyan; Li, Wenkai; Lu, Xiaoming; Xu, Yi; Li, Ruxin

    2016-07-01

    Broadband optical parametric amplification (OPA) in the near-infrared region (1.3-1.8 μm) is demonstrated in YCOB crystal pumped by 1 kHz Ti:sapphire based femtosecond laser at near critical wavelength degeneracy phase matching condition at first time. The gain bandwidth is closed to BIBO or BBO crystal OPA gain bandwidth. The energy obtained with 3.5 mm-thick YCOB reached 20 μJ with RMS 1.9%. After second harmonic generation, 17.6 fs pulse is obtained, and the pulse compressibility is demonstrated.

  17. Optimizing timing resolution for TOF PET detectors based on monolithic scintillation crystals using fast photosensor arrays

    NARCIS (Netherlands)

    Vinke, Ruud; Lohner, Herbert; Schaart, Dennis R.; van Dam, Herman T.; Seifert, Stefan; Beekman, Freek J.; Dendooven, Peter

    2009-01-01

    We have investigated the time-of-flight (TOF) capability of a monolithic 20 rum x 20 mm x 12 mm LYSO crystal coupled to a Hamamatsu position-sensitive H8711-03 4x4 multi-anode photomultiplier tube. The x-, y-, and z-coordinates of the photoconversion location inside the crystal are determined using

  18. Tunable flat band slow light in reconfigurable photonic crystal waveguides based on magnetic fluids

    DEFF Research Database (Denmark)

    Pu, Shengli; Wang, Haotian; Wang, Ning;

    2013-01-01

    A kind of two-dimensional photonic crystal line-defect waveguide with 45 -rotated square lattice is proposed to present slow light phenomena. Infiltrating the photonic crystal waveguide with appropriate magnetic fluids can generate very wide flat bands of guided modes, which give rise...

  19. Carbamazepine-Fumaric Acid Co-Crystal Screening Using Solution Based Method

    Directory of Open Access Journals (Sweden)

    Abd Rahim Syarifah

    2016-01-01

    Full Text Available Co-crystals is a multi-component system which connected by non-covalent interactions, present physically as a solid form under ambient conditions. Nowadays, co-crystal has becoming as an alternative approach to improve the bioavailability of poor water soluble drugs especially for a weakly ionisable groups or neutral compounds. In this study the co-crystal screening was carried out for carbamazepine (CBZ and fumaric acid (FUM co-crystal former (CCF using non-stoichiometric method (addition of CBZ to CCF saturated solution and stoichiometric method (evaporation of 1:1 molar ratio of CBZ to CCF in acetonitrile, ethyl acetate, propanol, ethanol and formic acid solvent systems. The crystals produced from the screening were characterized using Powder X-ray Diffraction (PXRD, Differential Scanning Calorimetry (DSC and Fourier Transform Infrared (FT-IR. The PXRD analysis had confirmed that the co-crystal was successfully formed in both methods for all of the solvent system studied with an exception to formic acid in the stoichiometric method where no crystal was found precipitate. The findings from this study revealed that Form A and Form B of CBZ-FUM co-crystal had been successfully formed from different solvent systems.

  20. Development of a task-based design approach for solution crystallization processes

    NARCIS (Netherlands)

    Lakerveld, R.

    2010-01-01

    Crystallization is historically one of the most important separation and product formation technologies in chemical industry. The future impact of crystallization is expected to increase as new high-added value products are often in crystalline form and need to comply with increasingly stringent pro

  1. Effects of crystallization fractions on mechanical properties of Zr-based metallic glass matrix composites

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The Zr41Ti14Cu12.5Ni10Be22.5 (at.%) bulk metallic glass composites with various crystallization fractions were prepared by pretreating the bulk metallic glassy samples with pulsing current, and then by isothermal annealing at near initial crystallization temperature for different periods of time. The precipitations and crystallization fractions were studied by X-ray diffraction (XRD) and differential scanning calorimetry (DSC), and their effects on mechanical properties of the composite were studied by microhardness, uniaxial compression test and scanning electron microscopy (SEM). The experimental results show that the primary precipitate is quasicrystalline phase and other metastable phases including Be2Zr, Zr2Cu and FCC would precipitate subsequently. In the initial crystallization process, in which the crystallization fraction increases from 0 to 8.2%, both fracture strength and plastic strain increase, with the maximum plastic strain up to 6.4%. When the crystallization fraction is larger than 8.2%, the fracture strength and the plastic strain decrease sharply. Furthermore, the alloy with low crystallization fraction is fractured by shearing, while for high crystallization fraction it is fractured by splitting and cleavage. The results show that the mechanical properties of the glassy alloy could be optimized by controlling the processing parameters.

  2. Thermo-tunable hybrid photonic crystal fiber based on solution-processed chalcogenide glass nanolayers.

    Science.gov (United States)

    Markos, Christos

    2016-01-01

    The possibility to combine silica photonic crystal fiber (PCF) as low-loss platform with advanced functional materials, offers an enormous range of choices for the development of fiber-based tunable devices. Here, we report a tunable hybrid silica PCF with integrated As2S3 glass nanolayers inside the air-capillaries of the fiber based on a solution-processed glass approach. The deposited high-index layers revealed antiresonant transmission windows from ~500 nm up to ~1300 nm. We experimentally demonstrate for the first time the possibility to thermally-tune the revealed antiresonances by taking advantage the high thermo-optic coefficient of the solution-processed nanolayers. Two different hybrid fiber structures, with core diameter 10 and 5 μm, were developed and characterized using a supercontinuum source. The maximum sensitivity was measured to be as high as 3.6 nm/°C at 1300 nm. The proposed fiber device could potentially constitute an efficient route towards realization of monolithic tunable fiber filters or sensing elements. PMID:27538726

  3. Touch sensors based on planar liquid crystal-gated-organic field-effect transistors

    Directory of Open Access Journals (Sweden)

    Jooyeok Seo

    2014-09-01

    Full Text Available We report a tactile touch sensor based on a planar liquid crystal-gated-organic field-effect transistor (LC-g-OFET structure. The LC-g-OFET touch sensors were fabricated by forming the 10 μm thick LC layer (4-cyano-4′-pentylbiphenyl - 5CB on top of the 50 nm thick channel layer (poly(3-hexylthiophene - P3HT that is coated on the in-plane aligned drain/source/gate electrodes (indium-tin oxide - ITO. As an external physical stimulation to examine the tactile touch performance, a weak nitrogen flow (83.3 μl/s was employed to stimulate the LC layer of the touch device. The LC-g-OFET device exhibited p-type transistor characteristics with a hole mobility of 1.5 cm2/Vs, but no sensing current by the nitrogen flow touch was measured at sufficiently high drain (VD and gate (VG voltages. However, a clear sensing current signal was detected at lower voltages, which was quite sensitive to the combination of VD and VG. The best voltage combination was VD = −0.2 V and VG = −1 V for the highest ratio of signal currents to base currents (i.e., signal-to-noise ratio. The change in the LC alignment upon the nitrogen flow touch was assigned as the mechanism for the present LC-g-OFET touch sensors.

  4. Backward Spectral Characterization of Liquid Crystal Display Based on Forward Spectral Characterization

    Directory of Open Access Journals (Sweden)

    Jian-qing Zhang

    2016-01-01

    Full Text Available A backward spectral characterization for Liquid Crystal Display by the use of rule for the maximum peak of spectral radiation curves changing with the digital input values is proposed; this new model is developed based on forward spectral characterization. It deals with estimation of RGB used as input to the digital display from known spectral radiation curves. We first investigate the rule for the peak of spectral radiation curves changing with the digital input values of primaries; then the initial digital input RGB are calculated based on that rule using the known spectral radiation curves ρ0. Third, RGB are inputted into forward spectral characterization model and the corresponding spectral radiation curves ρ1 are predicted. Last, RGB are modified according to the difference between predicted ρ1 and known ρ0, until this difference satisfied the prediction accuracy of the inverse characterization model. The inverse model has the advantage of using the same model for both forward and inverse color space transformation. This improves the accuracy of the color space transformation and reduces the source of errors. Results for 3 devices are shown and discussed; the accuracy of this model is considered sufficient for many applications.

  5. Ultrasensitive organic phototransistors with multispectral response based on thin-film/single-crystal bilayer structures

    Science.gov (United States)

    Pinto, R. M.; Gouveia, W.; Neves, A. I. S.; Alves, H.

    2015-11-01

    We report on highly efficient organic phototransistors (OPTs) based on thin-film/single-crystal planar bilayer junctions between 5,6,11,12-tetraphenyltetracene (rubrene) and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM). The OPTs show good field-effect characteristics in the dark, with high hole-mobility (4-5 cm2 V-1 s-1), low-contact resistance (20 kΩ cm), and low-operating voltage (≤5 V). Excellent sensing capabilities allow for light detection in the 400-750 nm range, with photocurrent/dark current ratio as high as 4 × 104, responsivity on the order of 20 AW-1 at 27 μW cm-2, and an external quantum efficiency of 52 000%. Photocurrent generation is attributed to enhanced electron and hole transfer at the interface between rubrene and PC61BM, and fast response times are observed as a consequence of the high-mobility of the interfaces. The optoelectronic properties exhibited in these OPTs outperform those typically provided by a-Si based devices, enabling future applications where multifunctionality in a single-device is sought.

  6. Ultrasensitive organic phototransistors with multispectral response based on thin-film/single-crystal bilayer structures

    Energy Technology Data Exchange (ETDEWEB)

    Pinto, R. M., E-mail: rpinto@inesc-mn.pt [INESC MN and IN, Rua Alves Redol 9, 1000-029 Lisboa (Portugal); CQFM, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Gouveia, W. [INESC MN and IN, Rua Alves Redol 9, 1000-029 Lisboa (Portugal); Neves, A. I. S. [INESC MN and IN, Rua Alves Redol 9, 1000-029 Lisboa (Portugal); College of Engineering, Mathematics and Physical Sciences, University of Exeter, EX4 4QL Exeter (United Kingdom); Alves, H. [INESC MN and IN, Rua Alves Redol 9, 1000-029 Lisboa (Portugal); CICECO, Physics Department, Universidade de Aveiro, 3810-193 Aveiro (Portugal)

    2015-11-30

    We report on highly efficient organic phototransistors (OPTs) based on thin-film/single-crystal planar bilayer junctions between 5,6,11,12-tetraphenyltetracene (rubrene) and [6,6]-phenyl-C{sub 61}-butyric acid methyl ester (PC{sub 61}BM). The OPTs show good field-effect characteristics in the dark, with high hole-mobility (4–5 cm{sup 2} V{sup −1} s{sup −1}), low-contact resistance (20 kΩ cm), and low-operating voltage (≤5 V). Excellent sensing capabilities allow for light detection in the 400–750 nm range, with photocurrent/dark current ratio as high as 4 × 10{sup 4}, responsivity on the order of 20 AW{sup −1} at 27 μW cm{sup −2}, and an external quantum efficiency of 52 000%. Photocurrent generation is attributed to enhanced electron and hole transfer at the interface between rubrene and PC{sub 61}BM, and fast response times are observed as a consequence of the high-mobility of the interfaces. The optoelectronic properties exhibited in these OPTs outperform those typically provided by a-Si based devices, enabling future applications where multifunctionality in a single-device is sought.

  7. Versatile hydrogel-based nanocrystal microreactors towards uniform fluorescent photonic crystal supraballs

    International Nuclear Information System (INIS)

    Versatile hydrogel-based nanocrystal (NC) microreactors were designed in this work for the construction of uniform fluorescence colloidal photonic crystal (CPC) supraballs. The hydrogel-based microspheres with sizes ranging from 150 to 300 nm were prepared by seeded copolymerization of acrylic acid and 2-hydroxyethyl methacrylate with micrometer-sized PS seed particles. As an independent NC microreactor, the as-synthesized hydrogel microsphere can effectively capture the guest cadmium ions due to the abundant carboxyl groups inside. Followed by the introduction of chalcogenides, in situ generation of higher-uptake NCs with sizes less than 5 nm was finally realized. Additionally, with the aid of the microfluidic device, the as-obtained NC–latex hybrids can be further self-assembled to bi-functional CPC supraballs bearing brilliant structural colors and uniform fluorescence. This research offers an alternative way to finely bind CPCs with NCs, which will facilitate progress in fields of self-assembled functional colloids and photonic materials

  8. MICROMECHANICS OF THE DAMAGE-INDUCED CELLULAR MICROSTRUCTURE IN SINGLE CRYSTAL Ni-BASED SUPERALLOYS

    Institute of Scientific and Technical Information of China (English)

    M.Sakaguchi; M.Okazaki

    2004-01-01

    An analytical method to investigate the morphological evolution of the cellular microstructure is explored and proposed. The method is essentially based on the Eshelby's micromechanics theory, and it is extended so as to be applied for a material system containing inclusions with high volume fraction, by employing the average stress field approximation by Mori and Tanaka. The proposed method enables us to discuss a stable shape of precipitate in the material system, which must be influenced by many factors: e.g., volume fraction of precipitate; Young's modulus ratio and lattice misfit between matrix and precipitate; external stress field in multiaxial state; and heterogeneity of plastic strain between matrix and precipitate. A series of numerical calculations were summarized on stable shape maps. The application of the method to predict the γ' rafting in superalloys during creep showed that the heterogeneity of plastic strain between matrix and precipitates may play a significant role in the shape stability of the precipitate. Furthermore, it was shown that the method was successfully applied to estimate the morphology of the cellular microstructure formed in CMSX-4single crystal Ni-based superalloy.

  9. Incorporating physically-based microstructures in materials modeling: Bridging phase field and crystal plasticity frameworks

    Science.gov (United States)

    Lim, Hojun; Abdeljawad, Fadi; Owen, Steven J.; Hanks, Byron W.; Foulk, James W.; Battaile, Corbett C.

    2016-05-01

    The mechanical properties of materials systems are highly influenced by various features at the microstructural level. The ability to capture these heterogeneities and incorporate them into continuum-scale frameworks of the deformation behavior is considered a key step in the development of complex non-local models of failure. In this study, we present a modeling framework that incorporates physically-based realizations of polycrystalline aggregates from a phase field (PF) model into a crystal plasticity finite element (CP-FE) framework. Simulated annealing via the PF model yields ensembles of materials microstructures with various grain sizes and shapes. With the aid of a novel FE meshing technique, FE discretizations of these microstructures are generated, where several key features, such as conformity to interfaces, and triple junction angles, are preserved. The discretizations are then used in the CP-FE framework to simulate the mechanical response of polycrystalline α-iron. It is shown that the conformal discretization across interfaces reduces artificial stress localization commonly observed in non-conformal FE discretizations. The work presented herein is a first step towards incorporating physically-based microstructures in lieu of the overly simplified representations that are commonly used. In broader terms, the proposed framework provides future avenues to explore bridging models of materials processes, e.g. additive manufacturing and microstructure evolution of multi-phase multi-component systems, into continuum-scale frameworks of the mechanical properties.

  10. Crystallization and structural investigation of Eu-doped fluorozirconate-based glass ceramics

    International Nuclear Information System (INIS)

    A series of Eu-doped fluorozirconate-based glass ceramics has been developed for medical and photovoltaic applications. In the first case, the materials can be used as X-ray scintillators or X-ray storage phosphors, in the latter case as down-converting top layers for highly efficient solar cells. The glasses are based on a modified ZBLAN composition, i.e. a mixture of Zr, Ba, La, Al, and Na fluorides. They are additionally doped with chlorine ions to initiate the growth of BaCl2 nanocrystals upon thermal processing. Eu2+ ions are incorporated into the nanocrystals during the annealing procedure enabling a strong fluorescence upon ultraviolet or x-ray excitation. The nanocrystal size and structural phase depend significantly on the heating conditions and Eu doping level. X-ray diffraction patterns show a structural phase change of the BaCl2 nanocrystals from hexagonal to orthorhombic as annealing temperatures are increased. DSC experiments were performed to obtain activation energies, thermal stability parameters and information on the crystal growth mechanisms.

  11. Versatile hydrogel-based nanocrystal microreactors towards uniform fluorescent photonic crystal supraballs

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jing; Tian, Yu; Ling, Lu-Ting; Yin, Su-Na; Wang, Cai-Feng; Chen, Su, E-mail: chensu-njut@163.com, E-mail: chensu@njtech.edu.cn [Nanjing Tech University, State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemistry and Chemical Engineering (China)

    2014-12-15

    Versatile hydrogel-based nanocrystal (NC) microreactors were designed in this work for the construction of uniform fluorescence colloidal photonic crystal (CPC) supraballs. The hydrogel-based microspheres with sizes ranging from 150 to 300 nm were prepared by seeded copolymerization of acrylic acid and 2-hydroxyethyl methacrylate with micrometer-sized PS seed particles. As an independent NC microreactor, the as-synthesized hydrogel microsphere can effectively capture the guest cadmium ions due to the abundant carboxyl groups inside. Followed by the introduction of chalcogenides, in situ generation of higher-uptake NCs with sizes less than 5 nm was finally realized. Additionally, with the aid of the microfluidic device, the as-obtained NC–latex hybrids can be further self-assembled to bi-functional CPC supraballs bearing brilliant structural colors and uniform fluorescence. This research offers an alternative way to finely bind CPCs with NCs, which will facilitate progress in fields of self-assembled functional colloids and photonic materials.

  12. Study of photoresponsivity in optoelectronic devices based on single crystal β-Ga2O3 epitaxial layers

    Science.gov (United States)

    Horng, Ray-Hua; Ravadgar, Parvaneh

    2013-03-01

    Single crystal β-Ga2O3 epitaxial layers have been prepared on c-axis (0001) sapphire substrates using metalorganic chemical vapor deposition technique at relatively low temperature. Post-annealing of β-Ga2O3 single crystals up to 800 °C does not affect the crystallinity, explored by x-ray diffraction, showing that β-Ga2O3 epitaxial layers are highly (-201) oriented. Metal-semiconductor-metal devices are fabricated on single crystals to study their photoresponsivity. A significant improvement in performance of post annealed-based devices is observed, attributed to point defect reduction. Annealing of as-grown samples results to a significant decrease in both oxygen and gallium vacancies, which are sources of current leakage.

  13. SYNTHESIS AND MESOMORPHIC PROPERTIES OF PALLADIUM CHELATES OF LIQUID CRYSTAL POLYSILOXANE WITH β-DIKETONE-BASED SIDE CHAINS

    Institute of Scientific and Technical Information of China (English)

    ZHOU Zhaohui; DAI Daorong; ZHANG Rongben

    1992-01-01

    A new type of palladium chelate of β-diketone-based side chain liquid crystal polysiloxane(Pd-DKLCP) has been synthesized by chelation reaction of palladium dichloride with polymeric ligand, β-diketone polysiloxane (DKLCP), using THF as solvent at R .T.. The Pd-chelation results in greatly increasing the phase transition temperature TK and the enthalpy change AHK from crystal to liquid crystal state and making the temperature range of LC state AT (A T=Tc1- TK) widened.All these chelates Pd-DKLCP's do not show TCl until decomposition at 205 ℃. It is noteworthy that the Pd-chelation can exert more positive effect on the mesomorphic behaviour of the polymer ligand than the counterpart Cu-DKLCP does. It is probable due to the bigger size of disc-like mesogen formed from β-diketone and Pd +2 ion with 4d orbital.

  14. Influence of pulsing current on the glass transition and crystallizing kinetics of a Zr base bulk amorphous alloy

    Institute of Scientific and Technical Information of China (English)

    WU Wenfei; YAO Kefu; ZHAO Zhankui

    2004-01-01

    Based on the thermal analysis, the influence of pulsing current on the glass transition and crystallizing kinetics of Zr41.3Ti14.2Cu12.8Ni10.3Be21.4 bulk amorphous alloy has been studied. The obtained results show that after the Zr41.3Ti14.2Cu12.8Ni10.3Be21.4 bulk amorphous alloy was pretreated by high-density pulsing current at low temperature, its glass transition temperature Tg, the initial crystallizing temperature Tx and the corresponding exothermic peak of crystallization Tpi were reduced. But the temperature range of supercooled liquid ΔT=Tx-Tg is almost the same. The calculated results with Kissinger equation show that the activation energy of glass transition of the alloy pretreated is reduced significantly, while the activation energy of crystallization is basically unchanged. The influence of pulsing current on the glass transition and crystallization of the Zr41.3Ti14.2Cu12.8Ni10.3Be21.4 bulk amorphous alloy is believed to be related with the structure relaxation of the glass caused by the current.

  15. Photosensitive structures based on CuIn{sub 5}Te{sub 8} single crystals: Development and properties

    Energy Technology Data Exchange (ETDEWEB)

    Bodnar, I. V. [Belarussian State University of Information Science and Radioelectronics (Belarus); Rud, V. Yu. [St. Petersburg State Polytechnical University (Russian Federation); Rud, Yu. V., E-mail: Yuryrud@mail.ioffe.ru; Terukov, E. I. [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation); Kovalchuk, A. M. [Belarussian State University of Information Science and Radioelectronics (Belarus)

    2011-05-15

    A new ternary compound is synthesized for the first time, and bulk CuIn{sub 5}Te{sub 8} single crystals are grown by directed crystallization of near-stoichiometric melt. It is established from X-ray diffraction patterns of grown crystals that they exhibit the structure of imperfect chalcopyrite with parameters of the unit cell of CuIn{sub 5}Te{sub 8}, which were close to those known for the CuInTe{sub 2} ternary compound with the composition index n = 0. First, photosensitive structures are fabricated based on CuIn{sub 5}Te{sub 8} crystals, and photosensitivity spectra are obtained for them; it is shown that it is possible to achieve broadband photosensitivity under illumination of the barrier side of these crystals. From the analysis of photosensitivity spectra, the character of band-to-band transitions and corresponding energies of these transitions in CuIn{sub 5}Te{sub 8} are determined. This opens up prospects to use this new semiconductor in photoconverters of solar radiation.

  16. Syntheses, crystal structures, anticancer activities of three reduce Schiff base ligand based transition metal complexes

    Science.gov (United States)

    Chang, Hui-Qin; Jia, Lei; Xu, Jun; Zhu, Tao-Feng; Xu, Zhou-Qing; Chen, Ru-Hua; Ma, Tie-Liang; Wang, Yuan; Wu, Wei-Na

    2016-02-01

    Three nickel(II) complexes, [Ni2(L1)2(tren)2(H2O)](ClO4)3 (1), [NiL2(tren)2](ClO4)·2.5H2O (2), [NiL2(tren)2]I·1.5H2O·CH3OH (3) based on amino acid reduced Schiff ligands are synthesized and characterized by physico-chemical and spectroscopic methods. The results show that in all complexes, the amino acid ligand is deprotonated and acts as an anionic ligand. In the dinuclear complex 1, each Ni(II) atom has a distorted octahedron geometry while with different coordination environment. However, the complexes 2 and 3 are mononuclear, almost with the same coordination environment. Furthermore, in vitro experiments are carried out, including MTT assay, Annexin V/PI flow cytometry and western blotting, to assess whether the complexes have antitumor effect. And the results show that all the three complexes have moderate anticancer activity towards human hepatic cancer (HepG2), human cervical cancer (HeLa) and human prostate (PC3) cell lines, in a concentration dependent way. The complex 1 exhibit higher cytotoxicity than the other two complexes and can induce human hepatic cancer cell (HepG2) to cell apoptosis by activating caspase 3.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-07-25

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

  18. Long-term evaluation of a liquid crystal polymer (LCP)-based retinal prosthesis

    Science.gov (United States)

    Jeong, Joonsoo; Bae, So Hyun; Seo, Jong-Mo; Chung, Hum; Kim, Sung June

    2016-04-01

    Objective. The aim of this study is to evaluate the long-term reliability of a recently presented liquid crystal polymer (LCP) -based retinal prosthesis in vitro as well as in vivo. Because an all-polymer implant introduces another intrinsic leak type due to gas permeation, for which the traditional helium leak test for metallic packages was not designed to quantify, a new method to investigate its durability is required. Approach. We designed and carried out a series of reliability tests specifically for all-polymer implants by quantitatively investigating moisture ingress through various pathways of the polymer surface, and the polymer-polymer and polymer-metal adhesions. Moisture permeation through the bulk material was estimated by analytic calculation, while water ingress through the adhesively sealed LCP-LCP and LCP-metal interfaces was investigated using the separate parts of an electrode array and a package in an accelerated aging condition. In vivo tests were done in rabbits to examine the long-term biocompatibility and implantation stability by fundus observation and optical coherence tomography (OCT) imaging. Main results. The analytic calculation estimated good barrier properties of the LCP. Samples of the LCP-based electrode array failed after 114 days in 87 °C saline as a result of water penetration through the LCP-metal interface. An eye-conformable LCP package survived for 87 days in an accelerated condition at 87 °C. The in vivo results confirmed that no adverse effects were observed around the retina 2.5 years after the implantation of the device. Significance. These long-term evaluation results show the potential for the chronic use of LCP-based biomedical implants to provide an alternative to traditional metallic packages.

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

    International Nuclear Information System (INIS)

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

  20. Converting Nonliquid Crystals into Liquid Crystals by N-Methylation in the Central Linker of Triazine-Based Dendrimers.

    Science.gov (United States)

    Tsai, Meng-Jung; Hsieh, Jei-Way; Lai, Long-Li; Cheng, Kung-Lung; Liu, Shih-Hsien; Lee, Jey-Jau; Hsu, Hsiu-Fu

    2016-06-17

    Two triazine-based dendrimers were successfully prepared in 60-75% yields. These newly prepared dendrimers 2a and 2b containing the -NMe(CH2)2NMe- and the -NMe(CH2)4NMe- linkers between two G3 dendrons, respectively, exhibit columnar phases during the thermal process. However, the corresponding dendrimers 1a and 1b containing the -NH(CH2)2NH- and the -NH(CH2)4NH- linkers between two G3 dendrons, respectively, do not show any LC phases on thermal treatment. Computational investigations on molecular conformations reveal that N-methylation of the dendritic central linker leads dendrimers to possess more isomeric conformations and thus successfully converts non-LC dendrimers (1a and 1b) into LC dendrimers (2a and 2b). PMID:27203100

  1. A MICROMECHANICAL MODEL FOR γ-TiAl BASE PST CRYSTALS

    Institute of Scientific and Technical Information of China (English)

    J.L. Su; G.K. Hu

    2005-01-01

    An analytical micromechanical method is proposed to examine the dependence of plastic deformation on the microstructure for a PST crystal. The sub-domain rnicrostructure of the γ phase and the effect of the α2 phase are taken into account by a proper micromechanical formulation,the dislocation slip and twinning deformation mechanisms are considered in the context of crystal plasticity. The model can well predict the dependence of stress-strain relations on loading angle with respect to the microstructure. The influence of the twinning and lamellar spacing on the deformation behavior and biaxial yield surfaces for PST crystals are also examined.

  2. Tunable photonic crystals based on ferroelectric and ferromagnetic materials by focused ion beam

    Institute of Scientific and Technical Information of China (English)

    Ziyou Zhou; Xiaoyue Huang; Raghav Vanga; Rong Li

    2007-01-01

    By making photonic crystals in ferroelectric and ferromagnetic materials, field-provoked tunability of photonic crystals is broadening the interest in new applications of on-chip photonic devices. We report a nano-precise fabrication of various designs of photonic crystals in these non-conventional materials using the focused ion beam milling technique. Standard methods are developed and parameters for different materials are calibrated. Optical responses such as bandgaps and polarization status changing from planar film waveguide system with these patterns have been examined on ferromagnetic materials.

  3. Design and analysis of a photonic crystal fiber based polarization filter using surface plasmon resonance

    Science.gov (United States)

    Yogalakshmi, S.; Selvendran, S.; Sivanantha Raja, A.

    2016-05-01

    A photonic crystal fiber with an active metal nanowire is proposed to act as a polarization filter based on the principle of plasmonic resonance. The light launched into the silica core gets coupled to gold wire inducing surface plasmon resonance, filtering one of the two orthogonally polarized light waves in the third optical communication window. This polarization filtering characteristic is analyzed using the finite element method. The change in the performance behaviour of the proposed filter is investigated by increasing the number of embedded gold wires, altering their positions and varying the diameter of gold wire. It is found that enhanced absorption of the core guided mode is achieved by replacing the filled metal nanowire with a metal coating around the air hole. Filtering of any or both polarizations can be attained by suitably positioning the metal wires. Confinement loss as high as 348.55 and 302 dB cm-1 for y-polarized and x-polarized lights respectively are attained at 1.52 and 1.56 μm respectively for single gold wire. The filter acts as a single polarization filter filtering x-polarized light with a confinement loss value of 187.67 dB cm-1 when two gold nanowires are placed adjacently. The same structure acts as the filter for y-polarized light by employing gold coating exhibiting an increased confinement loss of 406.34 dB cm-1 at 1.64 μm.

  4. Temperature dependence of deformation mechanism in single crystal Ni-base superalloy

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xuan; JIN Tao; ZHAO Nai-ren; WANG Zhi-hui; SUN Xiao-feng; GUAN Heng-rong; HU Zhuang-qi

    2005-01-01

    The tensile behavior of a new single crystal Ni-base superalloy was studied at various temperatures.Specimens were strained to fracture in the temperature range from 20 ℃ to 1 000 ℃. σ0.2 is essentially unaffected by temperatures between 20 ℃ and 400 ℃. At higher temperatures it increases until it reaches a maximum at about 800 ℃. Beyond 800 ℃ a sharp decrease of strength is observed. There is a slight fluctuation in ductility between 20 ℃ and 800 ℃. The elongation to fracture increases from 10% to 36% as the temperature increases from 800 ℃ to 1 000 ℃. The deformation is dominated by γ' shearing and the high-density dislocations are observed in matrix channels at low temperatures. The dislocation microstructure is inhomogeneous due to the formation of dislocation concentrations with high-density tangling at intermediate temperatures. The networks deposited at the γ'/γ'interfaces prevent dislocations from entering the γ' precipitates at high temperatures.

  5. Growth Stresses in Thermally Grown Oxides on Nickel-Based Single-Crystal Alloys

    Science.gov (United States)

    Rettberg, Luke H.; Laux, Britta; He, Ming Y.; Hovis, David; Heuer, Arthur H.; Pollock, Tresa M.

    2016-03-01

    Growth stresses that develop in α-Al2O3 scale that form during isothermal oxidation of three Ni-based single crystal alloys have been studied to elucidate their role in coating and substrate degradation at elevated temperatures. Piezospectroscopy measurements at room temperature indicate large room temperature compressive stresses in the oxides formed at 1255 K or 1366 K (982 °C or 1093 °C) on the alloys, ranging from a high of 4.8 GPa for René N4 at 1366 K (1093 °C) to a low of 3.8 GPa for René N5 at 1255 K (982 °C). Finite element modeling of each of these systems to account for differences in coefficients of thermal expansion of the oxide and substrate indicates growth strains in the range from 0.21 to 0.44 pct at the oxidation temperature, which is an order of magnitude higher than the growth strains measured in the oxides on intermetallic coatings that are typically applied to these superalloys. The magnitudes of the growth strains do not scale with the parabolic oxidation rate constants measured for the alloys. Significant spatial inhomogeneities in the growth stresses were observed, due to (i) the presence of dendritic segregation and (ii) large carbides in the material that locally disrupts the structure of the oxide scale. The implications of these observations for failure during cyclic oxidation, fatigue cycling, and alloy design are considered.

  6. Mono/dual-polarization refractive-index biosensors with enhanced sensitivity based on annular photonic crystals

    CERN Document Server

    Jiang, Liyong; Zhang, We; Li, Xiangyin

    2014-01-01

    To promote the development of two-dimensional (2D) photonic crystals (PCs) based refractive-index (RI) biosensors, there is an urgent requirement of an effective approach to improve the RI sensitivity of 2D PCs (usually less than 500 nm/RIU). In this work, the photonic band gap (PBG) feature and the corresponding RI sensitivity of the air-ring type 2D annular PCs (APCs) have been studied in detail. Such type of 2D PCs can easily and apparently improve the RI sensitivity in comparison with conventional air-hole type 2D PCs that have been widely studied in previous works. This is because the APCs can naturally exhibit suppressed up edge of PBG that can strongly affect the final RI sensitivity. In general, an enhanced sensing performance of as high as up to 2-3 times RI sensitivity can be obtained from pure 2D APCs. Such high RI sensitivity is also available in three typical waveguides developed from pure 2D APCs. Furthermore, a new conception of dual-polarization RI biosensors has been proposed by defining the ...

  7. Two Octaves Supercontinuum Generation in Lead-Bismuth Glass Based Photonic Crystal Fiber

    Directory of Open Access Journals (Sweden)

    Ryszard Buczynski

    2014-06-01

    Full Text Available In this paper we report a two octave spanning supercontinuum generation in a bandwidth of 700–3000 nm in a single-mode photonic crystal fiber made of lead-bismuth-gallate glass. To our knowledge this is the broadest supercontinuum reported in heavy metal oxide glass based fibers. The fiber was fabricated using an in-house synthesized glass with optimized nonlinear, rheological and transmission properties in the range of 500–4800 nm. The photonic cladding consists of 8 rings of air holes. The fiber has a zero dispersion wavelength (ZDW at 1460 nm. Its dispersion is determined mainly by the first ring of holes in the cladding with a relative hole size of 0.73. Relative hole size of the remaining seven rings is 0.54, which allows single mode performance of the fiber in the infrared range and reduces attenuation of the fundamental mode. The fiber is pumped into anomalous dispersion with 150 fs pulses at 1540 nm. Observed spectrum of 700–3000 nm was generated in 2 cm of fiber with pulse energy below 4 nJ. A flatness of 5 dB was observed in 950–2500 nm range.

  8. Microfabrication of color filter for liquid crystal display by inkjet-based method

    Science.gov (United States)

    Chen, Chin-Tai

    2002-09-01

    This paper explored a new micro-fabrication design of color filter for liquid crystal display, which was based on the so-called ink-jet technology today. Technically, a new type of micro-fluidic method was presented to realize the most important manufacturing steps of color filter that specific red, green, and blue ink droplets generated from the drop-on-demand jet heads could be accurately deposited onto a transparent substrate. Physically, those droplets were automatically formed very thin color films because of natural liquid surface tension between the droplets and substrate. To obtain the desired thickness of color film, high walls were made on the surface of the substrate to allow the droplets freely flow in essential one dimension under constraint of two neighboring walls before the film forming and drying. As a result, a color filter with desired striped pattern we designed could be simply completed; for example, the droplets of 60-micrometer diameter might be expected to yield a 110-micrometer by 110-micrometer pixel of color filter with color thickness of one micrometer. By comparison with current pigment-dispersed method, we estimated that similar chromatic performance in the final product could be achieved with much low cost and short manufacturing process in the presented method herein.

  9. A Reflective Photonic Crystal Fiber Temperature Sensor Probe Based on Infiltration with Liquid Mixtures

    Directory of Open Access Journals (Sweden)

    Congjing Hao

    2013-06-01

    Full Text Available In this paper, a reflective photonic crystal fiber (PCF sensor probe for temperature measurement has been demonstrated both theoretically and experimentally. The performance of the device depends on the intensity modulation of the optical signal by liquid mixtures infiltrated into the air holes of commercial LMA-8 PCFs. The effective mode field area and the confinement loss of the probe are both proved highly temperature-dependent based on the finite element method (FEM. The experimental results show that the reflected power exhibits a linear response with a temperature sensitivity of about 1 dB/°C. The sensor probe presents a tunable temperature sensitive range due to the concentration of the mixture components. Further research illustrates that with appropriate mixtures of liquids, the probe could be developed as a cryogenic temperature sensor. The temperature sensitivity is about 0.75 dB/°C. Such a configuration is promising for a portable, low-power and all-in-fiber device for temperature or refractive index monitoring in chemical or biosensing applications.

  10. Progress in hollow core photonic crystal fiber for atomic vapour based coherent optics

    Science.gov (United States)

    Bradley, T. D.; Wang, Y. Y.; Alharbi, M.; Fourcade Dutin, C.; Mangan, B. J.; Wheeler, N. V.; Benabid, F.

    2012-03-01

    We report on progress in different hollow core photonic crystal fiber (HC-PCF) design and fabrication for atomic vapor based applications. We have fabricated a Photonic bandgap (PBG) guiding HC-PCF with a record loss of 107dB/km at 785nm in this class of fiber. A double photonic bandgap (DPBG) guiding HC-PCF with guidance bands centred at 780nm and 1064nm is reported. A 7-cell 3-ring Kagome HC-PCF with hypocycloid core is reported, the optical loss at 780nm has been reduced to 70dB/km which to the best of our knowledge is the lowest optical loss reported at this wavelength using HC-PCF. Details on experimental loading of alkali metal vapours using a far off red detuned laser are reported. This optical loading has been shown to decrease the necessary loading time for Rb into the hollow core of a fiber. The quantity of Rb within the fiber core has been enhanced by a maximum of 14% through this loading procedure.

  11. X-ray crystal structure and activity of fluorenyl-based compounds as transthyretin fibrillogenesis inhibitors.

    Science.gov (United States)

    Ciccone, Lidia; Nencetti, Susanna; Rossello, Armando; Tepshi, Livia; Stura, Enrico A; Orlandini, Elisabetta

    2016-10-01

    Transthyretin (TTR) is a 54 kDa homotetrameric protein that transports thyroxine (T4) and retinol (vitamin A), through its association with retinol binding protein (RBP). Under unknown conditions, it aggregates to form fibrils associated with TTR amyloidosis. Ligands able to inhibit fibril formation have been studied by X-ray crystallography. The use of polyethylene glycol (PEG) instead of ammonium sulphate or citrate has been evaluated as an alternative to obtain new TTR complexes with (R)-3-(9-fluoren-9-ylideneaminooxy)-2-methyl-N-(methylsulfonyl) propionamide (48R(1)) and 2-(9H-fluoren-9-ylideneaminooxy) acetic acid (ES8(2)). The previously described fluorenyl based inhibitors (S)-3-((9H-fluoren-9-ylideneamino)oxy)-2-methylpropanoic acid (6BD) and 3-((9H-fluoren-9-ylideneamino)oxy)propanoic acid (7BD) have been re-evaluated with the changed crystallization method. The new TTR complexes with compounds of the same family show that the 9-fluorenyl motif can occupy alternative hydrophobic binding sites. This augments the potential use of this scaffold to yield a large variety of differently substituted mono-aryl compounds able to inhibit TTR fibril formation. PMID:26235916

  12. Terahertz polarization splitter based on orthogonal microstructure dual-core photonic crystal fiber.

    Science.gov (United States)

    Li, Shanshan; Zhang, Hao; Hou, Yu; Bai, Jinjun; Liu, Weiwei; Chang, Shengjiang

    2013-05-10

    A broadband polarization splitter operating in the terahertz (THz) band is proposed based on dual-core photonic crystal fiber with orthogonal microstructure in the core regions. The Index Converse Matching Coupling method is presented to design the THz polarization splitter for the first time, which exhibits several advantages, such as short splitting length, high extinction ratio, low loss, and broad operation bandwidth. By numerical simulation, it has been found that the strong coupling occurs within a frequency range of 0.4-0.7 THz. The operation bandwidth is more than 0.15 THz (equal to 138 μm). The shortest splitting length is only 1.83 cm at 0.4 THz. The extinction ratios for both of x and ypolarization are better than -15 dB when the frequency is larger than 0.51 THz. The lowest material absorption loss is only 0.34 dB at 0.4 THz. Moreover, this structure is simple to design and easy to fabricate over its counterparts in the communication band. Our research offers an effective method to design a broadband THz device and would be of significance for future relevant applications.

  13. A tiny gas-sensor system based on 1D photonic crystal

    Science.gov (United States)

    Bouzidi, A.; Bria, D.; Akjouj, A.; Pennec, Y.; Djafari-Rouhani, B.

    2015-12-01

    We present a gas monitoring system for detecting the gas concentration in ambient air. This sensor is based on a 1D photonic crystal formed by alternating layers of magnesium fluoride (MgF2) and silicon (Si) with an empty layer in the middle. The lamellar cavity (defect layer) will be filled with polluted air that has a refractive index close to that of pure air, varying between n 0  =  1.00 to n 0  =  1.01. The transmission spectrum of this sensor is calculated by the Green function approach. The numerical results show that the transmission peak, which appears in the gap, is caused by the infiltration of impure air into the empty middle layer. This transmission peak can be used for detection purposes in real-time environmental monitoring. The peak frequency is sensitive to the air-gas mixture, and a variation in the refractive index as small as Δn  =  10-5 can be detected. A sensitivity, Δλ/Δn, of 700 nm per refractive index unit (RIU) is achieved with this sensor.

  14. Self-collimation-based photonic crystal Mach–Zehnder add-drop filters

    International Nuclear Information System (INIS)

    Photonic crystal Mach–Zehnder add-drop filters (PC-MZADFs) based on the self-collimation phenomenon in a two-dimensional (2D) PC are proposed and numerically studied using finite-difference time-domain (FDTD) simulations. Each PC-MZADF is composed of a symmetric Mach–Zehnder interferometer (MZI) with an identical filter in each of its two different optical paths. Zizag-box resonators (ZBRs) and Fano resonators (FRs) are employed as the optical filters in rod-type and hole-type PCs, respectively. It is shown that self-collimated beams with the ZBR and FR resonant frequencies can be dropped or added using multiple-beam interference. We also show that the resonant frequencies of the resonators can be adjusted by varying the radii of their rods or holes. Our results indicate that this device design may constitute an efficient approach to light propagation manipulation and increase the application range of self-collimated beams. (paper)

  15. Single crystal growth of Al-based intermetallic phases being approximants to quasicrystals

    Science.gov (United States)

    Gille, Peter; Bauer, Birgitta; Hahne, Michael; Smontara, Ana; Dolinšek, Janez

    2011-03-01

    Decagonal (d) quasicrystals are formed in a number of Al-based ternary systems with d-AlCoNi being the best studied decagonal phase. They are highly anisotropic showing unusual properties of e.g. electric and thermal transport when measured along the periodic or quasiperiodic directions. For a long time, this has been attributed to the lack of periodicity in certain crystallographic orientations. Some neighbouring phases in the Al-Co-Ni system as well as in related ternaries consist of the same type of large icosahedral clusters, but are periodic in all three directions, sometimes with very large unit cells. Therefore, they are called approximants to the decagonal quasicrystals. They allow comparative studies of these phases as to judge whether some unusual properties of quasicrystals arise from the lack of periodicity or from the common atomic arrangements. Additional to decagonal AlCoNi quasicrystals, various approximants (monoclinic Al13(Co,Ni)4, orthorhombic Al13Co4, orthorhombic Al4(Cr,Fe), monoclinic Al13Fe4 and its ternary extensions Al13(Fe,Cr)4 and Al13(Fe,Ni)4) were grown by the Czochralski method as large single crystals as to carry out transport orientation-dependent measurements. It could be found that transport properties show remarkably similar anisotropic features when comparing corresponding crystallographic directions in these phases that can be related to the periodic stacking of layers.

  16. Active optics null test system based on a liquid crystal programmable spatial light modulator.

    Science.gov (United States)

    Ares, Miguel; Royo, Santiago; Sergievskaya, Irina; Riu, Jordi

    2010-11-10

    We present an active null test system adapted to test lenses and wavefronts with complex shapes and strong local deformations. This system provides greater flexibility than conventional static null tests that match only a precisely positioned, individual wavefront. The system is based on a cylindrical Shack-Hartmann wavefront sensor, a commercial liquid crystal programmable phase modulator (PPM), which acts as the active null corrector, enabling the compensation of large strokes with high fidelity in a single iteration, and a spatial filter to remove unmodulated light when steep phase changes are compensated. We have evaluated the PPM's phase response at 635 nm and checked its performance by measuring its capability to generate different amounts of defocus aberration, finding root mean squared errors below λ/18 for spherical wavefronts with peak-to-valley heights of up to 78.7λ, which stands as the limit from which diffractive artifacts created by the PPM have been found to be critical under no spatial filtering. Results of a null test for a complex lens (an ophthalmic customized progressive addition lens) are presented and discussed. PMID:21068848

  17. Single-crystal-silicon-based microinstrument to study friction and wear at MEMS sidewall interfaces

    International Nuclear Information System (INIS)

    Since the advent of microelectromechanical systems (MEMS) technology, friction and wear are considered as key factors that determine the lifetime and reliability of MEMS devices that contain contacting interfaces. However, to date, our knowledge of the mechanisms that govern friction and wear in MEMS is insufficient. Therefore, systematically investigating friction and wear at MEMS scale is critical for the commercial success of many potential MEMS devices. Specifically, since many emerging MEMS devices contain more sidewall interfaces, which are topographically and chemically different from in-plane interfaces, studying the friction and wear characteristics of MEMS sidewall surfaces is important. The microinstruments that have been used to date to investigate the friction and wear characteristics of MEMS sidewall surfaces possess several limitations induced either by their design or the structural film used to fabricate them. Therefore, in this paper, we report on a single-crystal-silicon-based microinstrument to study the frictional and wear behavior of MEMS sidewalls, which not only addresses some of the limitations of other microinstruments but is also easy to fabricate. The design, modeling and fabrication of the microinstrument are described in this paper. Additionally, the coefficients of static and dynamic friction of octadecyltrichlorosilane-coated sidewall surfaces as well as sidewall surfaces with only native oxide on them are also reported in this paper. (paper)

  18. Expression and functioning of retinal-based proton pumps in a saltern crystallizer brine.

    Science.gov (United States)

    Oren, Aharon; Abu-Ghosh, Said; Argov, Tal; Kara-Ivanov, Eliahu; Shitrit, Dror; Volpert, Adi; Horwitz, Rael

    2016-01-01

    We examined the presence of bacteriorhodopsin and other retinal protein pigments in the microbial community of the saltern crystallizer ponds in Eilat, Israel, and assessed the effect of the retinal-based proton pumps on the metabolic activity. The biota of the hypersaline (~309 g salts l(-1)) brine consisted of ~2200 β-carotene-rich Dunaliella cells and ~3.5 × 10(7) prokaryotes ml(-1), most of which were flat, square or rectangular Haloquadratum-like archaea. No indications were obtained for massive presence of Salinibacter. We estimated a concentration of bacteriorhodopsin and bacteriorhodopsin-like pigments of 3.6 nmol l(-1). When illuminated, the community respiration activity of the brine samples in which oxygenic photosynthesis was inhibited by 3-(3-4-dichlorophenyl)-1,1-dimethylurea, decreased by 40-43 %. This effect was interpreted to be the result of competition between two energy yielding systems: the bacteriorhodopsin proton pump and the respiratory chain. The results presented have important implications for the interpretation of many published data on photosynthetic and respiratory activities in hypersaline environments. PMID:26507954

  19. Crystal structure of 2-nitropropane dioxygenase complexed with FMN and substrate. Identification of the catalytic base.

    Science.gov (United States)

    Ha, Jun Yong; Min, Ji Young; Lee, Su Kyung; Kim, Hyoun Sook; Kim, Do Jin; Kim, Kyoung Hoon; Lee, Hyung Ho; Kim, Hye Kyung; Yoon, Hye-Jin; Suh, Se Won

    2006-07-01

    Nitroalkane compounds are widely used in chemical industry and are also produced by microorganisms and plants. Some nitroalkanes have been demonstrated to be carcinogenic, and enzymatic oxidation of nitroalkanes is of considerable interest. 2-Nitropropane dioxygenases from Neurospora crassa and Williopsis mrakii (Hansenula mrakii), members of one family of the nitroalkane-oxidizing enzymes, contain FMN and FAD, respectively. The enzymatic oxidation of nitroalkanes by 2-nitropropane dioxygenase operates by an oxidase-style catalytic mechanism, which was recently shown to involve the formation of an anionic flavin semiquinone. This represents a unique case in which an anionic flavin semiquinone has been experimentally observed in the catalytic pathway for oxidation catalyzed by a flavin-dependent enzyme. Here we report the first crystal structure of 2-nitropropane dioxygenase from Pseudomonas aeruginosa in two forms: a binary complex with FMN and a ternary complex with both FMN and 2-nitropropane. The structure identifies His(152) as the proposed catalytic base, thus providing a structural framework for a better understanding of the catalytic mechanism. PMID:16682407

  20. Design of photonic crystal-based all-optical AND gate using T-shaped waveguide

    Science.gov (United States)

    haq Shaik, Enaul; Rangaswamy, Nakkeeran

    2016-05-01

    We present a new configuration of all-optical AND gate based on two-dimensional photonic crystal composed of Si rods in air. Two AND gate structures with and without probe input are proposed. The proposed structures are designed with T-shaped waveguide without using nonlinear materials and optical amplifiers. The performance of the proposed AND gate structures is analyzed and simulated by plane-wave expansion and finite difference time domain methods. The AND gate without probe input needs only one T-shaped waveguide, whereas the AND gate with probe input needs two T-shaped waveguides. The former AND gate offers a bit rate of 6.26 Tbps with a contrast ratio of 5.74 dB, whereas the latter AND gate offers a bit rate of 3.58 Tbps whose contrast ratio is 9.66 dB. It can be expected that these small size T-shaped structures are suitable for large-scale integration and can potentially be used in on-chip photonic integrated circuits.

  1. Influence of microstructure stability on creep properties of single crystal nickel base superalloys

    Institute of Scientific and Technical Information of China (English)

    TIAN Su-gui; MENG Fan-lai; DU Hong-qiang; WANG Chun-tao; SHUI Li; HU Zhuang-qi

    2006-01-01

    The influence of microstructure stability on the creep properties of single crystal nickel-based superalloys was investigated by means of the measurement of the creep curves and microstructure observation. Results show that the superalloy with 4%(mass fraction)W in Ni-Al-Cr-Ta-Co-5.5%Mo-x%W systems displays a better microstructure stability, but the μphase is precipitated in the superalloy with 6% W during aging. The strip-like μphase is precipitated to be parallel or perpendicular to each other along the orientation, and grown into the slice-like morphology along the {111} planes. The superalloy with 4%W displays a better creep rupture lifetime under the applied stress of 200 MPa at 982 oC, but the creep lifetime of alloy is obviously decreased with the increase of the element W content up to 6%. The fact that the μphase is precipitated in the superalloy with 6% W during applied stress and unstress aging results in the appearance of the poor regions for the refractory elements. This is one of the main reasons for reducing the creep rupture lifetime of the superalloy.

  2. Self-collimation-based photonic crystal Mach-Zehnder add-drop filters

    Science.gov (United States)

    Lee, Sun-Goo; Park, Jong-Moon; Kee, Chul-Sik; Lee, Jongjin

    2016-02-01

    Photonic crystal Mach-Zehnder add-drop filters (PC-MZADFs) based on the self-collimation phenomenon in a two-dimensional (2D) PC are proposed and numerically studied using finite-difference time-domain (FDTD) simulations. Each PC-MZADF is composed of a symmetric Mach-Zehnder interferometer (MZI) with an identical filter in each of its two different optical paths. Zizag-box resonators (ZBRs) and Fano resonators (FRs) are employed as the optical filters in rod-type and hole-type PCs, respectively. It is shown that self-collimated beams with the ZBR and FR resonant frequencies can be dropped or added using multiple-beam interference. We also show that the resonant frequencies of the resonators can be adjusted by varying the radii of their rods or holes. Our results indicate that this device design may constitute an efficient approach to light propagation manipulation and increase the application range of self-collimated beams.

  3. Active optics null test system based on a liquid crystal programmable spatial light modulator

    Energy Technology Data Exchange (ETDEWEB)

    Ares, Miguel; Royo, Santiago; Sergievskaya, Irina; Riu, Jordi

    2010-11-10

    We present an active null test system adapted to test lenses and wavefronts with complex shapes and strong local deformations. This system provides greater flexibility than conventional static null tests that match only a precisely positioned, individual wavefront. The system is based on a cylindrical Shack-Hartmann wavefront sensor, a commercial liquid crystal programmable phase modulator (PPM), which acts as the active null corrector, enabling the compensation of large strokes with high fidelity in a single iteration, and a spatial filter to remove unmodulated light when steep phase changes are compensated. We have evaluated the PPM's phase response at 635 nm and checked its performance by measuring its capability to generate different amounts of defocus aberration, finding root mean squared errors below {lambda}/18 for spherical wavefronts with peak-to-valley heights of up to 78.7{lambda}, which stands as the limit from which diffractive artifacts created by the PPM have been found to be critical under no spatial filtering. Results of a null test for a complex lens (an ophthalmic customized progressive addition lens) are presented and discussed.

  4. Syntheses, crystal structures, and properties of four complexes based on polycarboxylate and imidazole ligands

    Energy Technology Data Exchange (ETDEWEB)

    Qiao, Rui [School of Chemistry and Chemical Engineering, Fuyang University, Fuyang 236041 (China); Chen, Shui-Sheng, E-mail: chenss@fync.edu.cn [School of Chemistry and Chemical Engineering, Fuyang University, Fuyang 236041 (China); Coordination Chemistry Institute, State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093 (China); Sheng, Liang-Quan; Yang, Song; Li, Wei-Dong [School of Chemistry and Chemical Engineering, Fuyang University, Fuyang 236041 (China)

    2015-08-15

    Four metal–organic coordination polymers [Zn(HL)(H{sub 2}O)]·4H{sub 2}O (1), [Zn(HL)(L{sub 1})]·4H{sub 2}O (2), [Cu(HL)(H{sub 2}O)]·3H{sub 2}O (3) and [Cu(HL)(L{sub 1})]·5H{sub 2}O (4) were synthesized by reactions of the corresponding metal(II) salts with semirigid polycarboxylate ligand (5-((4-carboxypiperidin-1-yl)methyl)isophthalic acid hydrochloride, H{sub 3}L·HCl) or auxiliary ligand (1,4-di(1H-imidazol-4-yl)benzene, L{sub 1}). The structures of the compounds were characterized by elemental analysis, FT-IR spectroscopy and single-crystal X-ray diffraction. The use of auxiliary ligand L{sub 1} has great influence on the structures of two pairs of complexes 1, 2 and 3, 4. Complex 1 is a uninodal 3-connected rare 2-fold interpenetrating ZnSc net with a Point (Schlafli) symbol of (10{sup 3}) while 2 is a one-dimensional (1D) ladder structure. Compound 3 features a two-dimensional (2D) honeycomb network with typical 6{sup 3}-hcb topology, while 4 is 2D network with (4, 4) sql topology based on binuclear Cu{sup II} subunits. The non-covalent bonding interactions such as hydrogen bonds, π···π stacking and C–H···π exist in complexes 1–4, which contributes to stabilize crystal structure and extend the low-dimensional entities into high-dimensional frameworks. And the photoluminescent property of 1 and 2 and gas sorption property of 4 have been investigated. - Graphical abstract: Four new coordination polymers have been obtained and their photoluminescent and gas sorption properties have also been investigated. - Highlights: • Two pairs of Zn{sup II}/ Cu{sup II} compounds have been synthesized. • Auxiliary ligand-controlled assembly of the complexes is reported. • The luminescent properties of complexes 1–2 were investigated. • The gas sorption property of 4 has been investigated.

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

    Science.gov (United States)

    Wasson, Andrew Jay

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

  6. High-performance Refractive Index Sensor Based on Photonic Crystal Single Mode Resonant Micro-cavity

    Institute of Scientific and Technical Information of China (English)

    Shengye Huang; Junfeng Shi; Dongsheng Wang; Wei Li

    2006-01-01

    An effective refractive index sensor built with square lattice photonic crystal is proposed, which can be applicable to photonic integrated circuits. Two photonic crystal waveguides rather than conventional ridge waveguides are used as entrance/exit waveguides to the micro-cavity. Three layers of photonic lattice are set between the photonic crystal waveguides and the micro-cavity to achieve both a high transmission and a high sensitivity. The plane wave method is utilized to calculate the disperse curves and the finite difference time domain scheme is employed to simulate the light propagation. At the resonant wavelength of about 1500 nm, the resonant wavelength shifts up by 0.7 nm for each increment of △n=0.001. A transmission of more than 0.75 is observed. Although the position disorder of the photonic crystal doesn't affect the sensitivity of the sensor,the transmission reduces rapidly as the disorder increases.

  7. A Raman cell based on hollow core photonic crystal fiber for human breath analysis

    Energy Technology Data Exchange (ETDEWEB)

    Chow, Kam Kong; Zeng, Haishan, E-mail: hzeng@bccrc.ca [Imaging Unit – Integrative Oncology Department, British Columbia Cancer Agency Research Centre, 675 West 10th Avenue, Vancouver, British Columbia V5Z 1L3, Canada and Medical Physics Program – Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, British Columbia V6T 1Z1 (Canada); Short, Michael; Lam, Stephen; McWilliams, Annette [Imaging Unit – Integrative Oncology Department, British Columbia Cancer Agency Research Centre, 675 West 10th Avenue, Vancouver, British Columbia V5Z 1L3 (Canada)

    2014-09-15

    Purpose: Breath analysis has a potential prospect to benefit the medical field based on its perceived advantages to become a point-of-care, easy to use, and cost-effective technology. Early studies done by mass spectrometry show that volatile organic compounds from human breath can represent certain disease states of our bodies, such as lung cancer, and revealed the potential of breath analysis. But mass spectrometry is costly and has slow-turnaround time. The authors’ goal is to develop a more portable and cost effective device based on Raman spectroscopy and hollow core-photonic crystal fiber (HC-PCF) for breath analysis. Methods: Raman scattering is a photon-molecular interaction based on the kinetic modes of an analyte which offers unique fingerprint type signals that allow molecular identification. HC-PCF is a novel light guide which allows light to be confined in a hollow core and it can be filled with a gaseous sample. Raman signals generated by the gaseous sample (i.e., human breath) can be guided and collected effectively for spectral analysis. Results: A Raman-cell based on HC-PCF in the near infrared wavelength range was developed and tested in a single pass forward-scattering mode for different gaseous samples. Raman spectra were obtained successfully from reference gases (hydrogen, oxygen, carbon dioxide gases), ambient air, and a human breath sample. The calculated minimum detectable concentration of this system was ∼15 parts per million by volume, determined by measuring the carbon dioxide concentration in ambient air via the characteristic Raman peaks at 1286 and 1388 cm{sup −1}. Conclusions: The results of this study were compared to a previous study using HC-PCF to trap industrial gases and backward-scatter 514.5 nm light from them. The authors found that the method presented in this paper has an advantage to enhance the signal-to-noise ratio (SNR). This SNR advantage, coupled with the better transmission of HC-PCF in the near-IR than in the

  8. Interactions between high temperature deformation and crystallization in zirconium based bulk metallic glasses

    OpenAIRE

    Gravier, Sébastien; Blandin, Jean-Jacques; Donnadieu, Patricia

    2008-01-01

    Abstract High temperature deformation of a ZrTiCuNiBe bulk metallic glass (BMG) is investigated by compression tests in the supercooled liquid region. When temperature is decreased or strain rate is increased, the amorphous alloy exhibits the usual Newtonian ? non Newtonian behavior transition. Owing to appropriate heat treatments, partially crystallized alloys are produced, the associated microstructures are characterized and the volume fractions of crystal are measured. The inter...

  9. Young tableaux and crystal base for U_q(osp(1|2n))

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Let Uq(osp(1|2n)) be the quantized enveloping superalgebra corresponding to the Lie superalgebra osp(1|2n). In terms of semistandard Young tableaux satisfying some additional conditions, a realization of crystal graph of finite-dimensional irreducible modules of Uq(osp(1|2n)) is given. Also, the generalized LittlewoodRichardson rule for tensor product of crystal graphs is established.

  10. Touch sensors based on planar liquid crystal-gated-organic field-effect transistors

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Jooyeok; Lee, Chulyeon; Han, Hyemi; Lee, Sooyong; Nam, Sungho; Kim, Youngkyoo, E-mail: ykimm@knu.ac.kr [Organic Nanoelectronics Laboratory, Department of Chemical Engineering and Graduate School of Applied Chemical Engineering, Kyungpook National University, Daegu, 702-701 (Korea, Republic of); Kim, Hwajeong [Organic Nanoelectronics Laboratory, Department of Chemical Engineering and Graduate School of Applied Chemical Engineering, Kyungpook National University, Daegu, 702-701 (Korea, Republic of); Priority Research Center, Research Institute of Advanced Energy Technology, Kyungpook National University, Daegu, 702-701 (Korea, Republic of); Lee, Joon-Hyung [School of Materials Science and Engineering, Kyungpook National University, Daegu, 702-701 (Korea, Republic of); Park, Soo-Young; Kang, Inn-Kyu [Department of Polymer Science and Engineering and Graduate School of Applied Chemical Engineering, Kyungpook National University, Daegu, 702-701 (Korea, Republic of)

    2014-09-15

    We report a tactile touch sensor based on a planar liquid crystal-gated-organic field-effect transistor (LC-g-OFET) structure. The LC-g-OFET touch sensors were fabricated by forming the 10 μm thick LC layer (4-cyano-4{sup ′}-pentylbiphenyl - 5CB) on top of the 50 nm thick channel layer (poly(3-hexylthiophene) - P3HT) that is coated on the in-plane aligned drain/source/gate electrodes (indium-tin oxide - ITO). As an external physical stimulation to examine the tactile touch performance, a weak nitrogen flow (83.3 μl/s) was employed to stimulate the LC layer of the touch device. The LC-g-OFET device exhibited p-type transistor characteristics with a hole mobility of 1.5 cm{sup 2}/Vs, but no sensing current by the nitrogen flow touch was measured at sufficiently high drain (V{sub D}) and gate (V{sub G}) voltages. However, a clear sensing current signal was detected at lower voltages, which was quite sensitive to the combination of V{sub D} and V{sub G}. The best voltage combination was V{sub D} = −0.2 V and V{sub G} = −1 V for the highest ratio of signal currents to base currents (i.e., signal-to-noise ratio). The change in the LC alignment upon the nitrogen flow touch was assigned as the mechanism for the present LC-g-OFET touch sensors.

  11. A Dibutyl Phthalate Sensor Based on a Nanofiber Polyaniline Coated Quartz Crystal Monitor

    Directory of Open Access Journals (Sweden)

    Guang Li

    2013-03-01

    Full Text Available Dibutyl phthalate (DBP is a commonly used plasticizer and additive to adhesives, printing inks and nail polishes. Because it has been found to be a powerful reproductive and developmental toxicant, a sensor to monitor DBP in some working spaces and the environment is required. In this work polyaniline nanofibers were deposited on the electrode of a quartz crystal oscillator to form a Quartz Crystal Microbalance gas sensor. The coated quartz crystal and a non-coated quartz crystal were mounted in a sealed chamber, and their frequency difference was monitored. When DBP vapor was injected into the chamber, gas adsorption decreased the frequency of the coated quartz crystal oscillator and thereby caused an increase in the frequency difference between the two crystals. The change of the frequency difference was recorded as the sensor response. The sensor was extremely sensitive to DBP and could be easily recovered by N2 purging. A low measurement limit of 20 ppb was achieved. The morphologies of the polyaniline films prepared by different approaches have been studied by SEM and BET. How the nanofiber-structure can improve the sensitivity and stability is discussed, while its selectivity and long-term stability were investigated.

  12. Evanescent Field Enhancement in Liquid Crystal Optical Fibers: A Field Characteristics Based Analysis

    Directory of Open Access Journals (Sweden)

    P. K. Choudhury

    2013-01-01

    Full Text Available The paper presents the analysis of the electromagnetic wave propagation through liquid crystal optical fibers (LCOFs of two different types—conventional guides loaded with liquid crystals (addressed as LCOFs and those with additional twists due to conducting helical windings (addressed as HCLCOFs. More precisely, the three-layer optical waveguide structures are considered along with its outermost region being loaded with radially anisotropic liquid crystal material and the inner regions being made of usual silica, as used in conventional optical fibers. In addition to that, LCOF with twists introduced in the form of conducting helical windings at the interface of the silica core and the liquid crystal clad is also taken into account. Emphasis has been put on the power confinements by the lower-order TE modes sustained in the different sections of the LCOF structure. The results demonstrate useful applications of these guides in integrated optics as the power sustained in the liquid crystal section by the excited TE modes remains very high. In the case of twisted clad liquid crystal guides, descriptions are limited to the nature of dispersion relation only under the TE mode excitation, and corresponding to the cases of helix orientations being parallel and perpendicular to the optical axis.

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

    Directory of Open Access Journals (Sweden)

    Guangqiang Liu

    2016-09-01

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

  14. Artistic Crystal Creations

    Science.gov (United States)

    Lange, Catherine

    2008-01-01

    In this inquiry-based, integrative art and science activity, Grade 5-8 students use multicolored Epsom salt (magnesium sulfate) crystallizing solutions to reveal beautiful, cylindrical, 3-dimensional, needle-shaped structures. Through observations of the crystal art, students analyze factors that contribute to crystal size and formation, compare…

  15. Separation of 1,3-propanediol from glycerol-based fermentations of Klebsiella pneumoniae by alcohol precipitation and dilution crystallization

    Institute of Scientific and Technical Information of China (English)

    GAO Sujun; ZHANG Daijia; SUN Yaqin; XIU Zhilong

    2007-01-01

    The separation of 1,3-propanediol from the glycerol-based fermentation broth of Klebsiella pneumoniae plays an important role during the microbial production of 1,3-propanediol.In this paper,the separation of 1,3-propanediol from fermentative broth by a combination of ultrafiltration and alcohol dilution crystallization was investigated.The broth was first filtered by ultrafiltration,and 99%of cells,89.4% of proteins and 69% of nucleic acids were removed.The obtained broth was further condensed by vacuum distillation,and then alcohol was added.The macromolecular impurities,such as nucleic acids,polysaccharides and proteins,were precipitated,and inorganic and organic salts were crystallized.The optimal volume ratio of alcohol added to the condensed fermentation broth was determined to tivity decreased by 97.4%,89.7% and 95.8%,respectively,compared with the fermentative broth.The influences of pH and water content in condensed broth on alcohol precipitation and dilution crystallization were also investigated.The experimental results indicated that alcohol precipitation and dilution crystallization was feasible and effective for the separation of 1,3-propanediol from actual fermentation broth.

  16. Self-assembled hybrid materials based on conjugated polymers and semiconductors nano-crystals for plastic solar cells

    International Nuclear Information System (INIS)

    This work is devoted to the elaboration of self-assembled hybrid materials based on poly(3- hexyl-thiophene) and CdSe nano-crystals for photovoltaic applications. For that, complementary molecular recognition units were introduced as side chain groups on the polymer and at the nano-crystals' surface. Diamino-pyrimidine groups were introduced by post-functionalization of a precursor copolymer, namely poly(3-hexyl-thiophene-co-3- bromo-hexyl-thiophene) whereas thymine groups were introduced at the nano-crystals' surface by a ligand exchange reaction with 1-(6-mercapto-hexyl)thymine. However, due to their different solubility, the mixing of the two components by solution processes is difficult. A 'one-pot' procedure was developed, but this method led to insoluble aggregates without control of the hybrid composition. To overcome the solubility problem, the layer-by-layer method was used to prepare the films. This method allows a precise control of the deposition process. Experimental parameters were tested in order to evaluate their impact on the resulting film. The films morphology was investigated by microscopy and X-Ray diffraction techniques. These analyses reveal an interpenetrated structure of nano-crystals within the polymer matrix rather than a multilayered structure. Electrochemical and spectro electrochemical studies were performed on the hybrid material deposited by the LBL process. Finally the materials were tested in a solar cell configuration and the I=f(V) curves reveals a clear photovoltaic behaviour. (author)

  17. Crystallization of copper(II) sulfate based minerals and MOF from solution: Chemical insights into the supramolecular interactions

    Indian Academy of Sciences (India)

    M Singh; D Kumar; J Thomas; A Ramanan

    2010-09-01

    Crystallization of solids, molecular or non-molecular from solution is a supramolecular reaction. Nucleation of a lattice structure at supersaturation can be conceived to result from a critical nucleus, a high energy intermediate (supramolecular transition state). Conceptualization of a structure for the critical nucleus in terms of aggregation of tectons through non-covalent interactions provides chemical insights into the architecture of a solid. The retrosynthetic analysis of copper-based minerals and materials offers an elegant description for the crystal packing. It addresses the influence of the geometry, functionality and reactivity of copper tecton(s) in directing a specific supramolecular aggregation. The mechanistic approach provides guiding principles to chemists to account for the experimentally crystallized solids and a platform to practice structure-synthesis correlation. Rationalization of the same composition with different atomic arrangements (polymorphs), compositional variation leading to different pseudopolymorphs, degree of hydration (anhydrous to hydrated), water clusters, role of solvent, etc. can all be justified on molecular basis. Also, the method gives predictive components including directions to synthesize new solids. In a nutshell, the paper is an attempt to generalize the crystallization of inorganic solids from solution by recognizing supramolecular interactions between metal tectons and gain insights for designing new MOF.

  18. Automated detection and characterization of microstructural features: application to eutectic particles in single crystal Ni-based superalloys

    International Nuclear Information System (INIS)

    Serial sectioning methods continue to produce an abundant amount of image data for quantifying the three-dimensional nature of material microstructures. Here, we discuss a methodology to automate detecting and characterizing eutectic particles taken from serial images of a production turbine blade made of a heat-treated single crystal Ni-based superalloy (PWA 1484). This method includes two important steps for unassisted eutectic particle characterization: automatically identifying a seed point within each particle and segmenting the particle using a region growing algorithm with an automated stop point. Once detected, the segmented eutectic particles are used to calculate microstructural statistics for characterizing and reconstructing statistically representative synthetic microstructures for single crystal Ni-based superalloys. The significance of this work is its ability to automate characterization for analysing the 3D nature of eutectic particles

  19. A Crystallization Study of Nanocrystalline PZT 53/47Granular Arrays Using a Sol-Gel Based Precursor

    Institute of Scientific and Technical Information of China (English)

    A. Suárez-Gómez; J.M. Saniger-Blesa; F. Calderón-Pi(n)ar

    2011-01-01

    In this work, we intend to perform a detailed study on the crystallization process of PZT 53/47 nanostructured powders by starting out with an amorphous precursor synthesized by a sol-gel based solution. Our interests also lie in the feasibility for controlling the average grain size of the final structure in the submicron range on an ab initio basis. Purposely, Fourier transform infrared spectroscopy (FT-IR), Raman (Stokes and Anti-Stokes), X-ray diffraction (XRD) and scanning electron microscopy (SEM) are used to examine the microstructural characteristics based on previously reported differential thermal analysis/thermal gravimetric analysis (DTA/TGA) data. The results show a crystallization temperature of 800℃ to attain pure perovskite phase with excellent morphological quality, average grain size <DG>< 300 nm and with average crystallite size <DC><15 nm.

  20. Automated detection and characterization of microstructural features: application to eutectic particles in single crystal Ni-based superalloys

    Science.gov (United States)

    Tschopp, M. A.; Groeber, M. A.; Fahringer, R.; Simmons, J. P.; Rosenberger, A. H.; Woodward, C.

    2010-03-01

    Serial sectioning methods continue to produce an abundant amount of image data for quantifying the three-dimensional nature of material microstructures. Here, we discuss a methodology to automate detecting and characterizing eutectic particles taken from serial images of a production turbine blade made of a heat-treated single crystal Ni-based superalloy (PWA 1484). This method includes two important steps for unassisted eutectic particle characterization: automatically identifying a seed point within each particle and segmenting the particle using a region growing algorithm with an automated stop point. Once detected, the segmented eutectic particles are used to calculate microstructural statistics for characterizing and reconstructing statistically representative synthetic microstructures for single crystal Ni-based superalloys. The significance of this work is its ability to automate characterization for analysing the 3D nature of eutectic particles.

  1. Characterization of a high-power piezoelectric energy-scavenging device based on PMN-PT piezoelectric single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Moon, S. E.; Lee, S. K.; Lee, Y. G.; Kim, K. M.; Yang, Y. S.; Yang, W. S.; Kim, J. [Electronics and Telecommunications Research Institute, Daejeon (Korea, Republic of)

    2012-01-15

    In this paper, we present the calculations and the results for vibration-energy-scavenging performances based on a piezoelectric single-crystal beam. Using the measured mechanical damping ratio and electro-mechanical coupling coefficient of a novel cantilever structure device, we calculated the output performances and compared them with the measured results. A device based on a bimorph cantilever structure with a proof mass was designed to have a natural resonance frequency of about 60 Hz, and the energy-scavenging capability of piezoelectric single crystal was measured. The results showed that several tens of AC volts and a few milliwatts power were achieved under a 0.1 g{sub rms} vibration condition. Also using this device and a commercial power management circuit, we performed Li-ion battery charging experiment.

  2. On Post-Weld Heat Treatment of a Single Crystal Nickel-Based Superalloy Joint by Linear Friction Welding

    Directory of Open Access Journals (Sweden)

    T. J. Ma

    2015-09-01

    Full Text Available Three types of post-weld heat treatment (PWHT, i.e. solution treatment + primary aging + secondary aging (I, secondary aging (II, and primary aging + secondary aging (III, were applied to a single crystal nickel-based superalloy joint made with linear friction welding (LFW. The results show that the grains in the thermomechanically affected zone (TMAZ coarsen seriously and the primary γ' phase in the TMAZ precipitates unevenly after PWHT I. The primary γ' phase in the TMAZ and weld zone (WZ precipitates insufficiently and fine granular secondary γ' phase is observed in the matrix after PWHT II. After PWHT III, the primary γ' phase precipitates more sufficiently and evenly compared to PWHTs I and II. Moreover, the grains in the TMAZ have not coarsened seriously and fine granular secondary γ' phase is not found after PWHT III. PWHT III seems more suitable to the LFWed single crystal nickel-based superalloy joints when performing PWHT.

  3. Reflection mode two-dimensional photonic-crystal-slab-waveguide-based micropressure sensor

    Science.gov (United States)

    Wang, Yi; Bakhtazad, Aref; Sabarinathan, Jayshri

    2011-08-01

    Photonic crystals (PhCs) have recently been the focus for the developing micro- and nano-optical sensors, due to its capability to control and manipulate light on planar devices. This paper presents a novel design of micro-optical pressure sensor based on 2-dimensional PhC slab suspended on Si substrate. A line defect was introduced to the PhC slab to guide and reflect light with frequency in the photonic bandgap in the plane of the slab. The structure, with certain surface treatment, can be used in miro-scale pressure catheters in heart ablation surgeries and other biomedical applications. The working principle of the device is to modify light reflection in the PhC line defect waveguide by moving a substrate vertically in the evanescent field of the PhC waveguide. Evanescent field coupling is the critical step that affects light transmission and reflection. High resolution electron-beam lithography and isotropic wet etching have been used to realize the device on the top layer of a Si-On-Insulator (SOI) wafer. The PhC slab is released by isotropic wet etch of the berried oxide layer. The output reflection spectrum of the device under different pressure conditions is simulated using 3-dimensional finite difference time domain (FDTD) method. The result showed that when the PhC slab is close enough to the substrate (less than 400 nm), the reflected light intensity decreases sharply when the substrate moves towards the PhC slab. Mechanical response of the sensor is also studied.

  4. GWAS-based pathway analysis differentiates between fluid and crystallized intelligence.

    Science.gov (United States)

    Christoforou, A; Espeseth, T; Davies, G; Fernandes, C P D; Giddaluru, S; Mattheisen, M; Tenesa, A; Harris, S E; Liewald, D C; Payton, A; Ollier, W; Horan, M; Pendleton, N; Haggarty, P; Djurovic, S; Herms, S; Hoffman, P; Cichon, S; Starr, J M; Lundervold, A; Reinvang, I; Steen, V M; Deary, I J; Le Hellard, S

    2014-09-01

    Cognitive abilities vary among people. About 40-50% of this variability is due to general intelligence (g), which reflects the positive correlation among individuals' scores on diverse cognitive ability tests. g is positively correlated with many life outcomes, such as education, occupational status and health, motivating the investigation of its underlying biology. In psychometric research, a distinction is made between general fluid intelligence (gF) - the ability to reason in novel situations - and general crystallized intelligence (gC) - the ability to apply acquired knowledge. This distinction is supported by developmental and cognitive neuroscience studies. Classical epidemiological studies and recent genome-wide association studies (GWASs) have established that these cognitive traits have a large genetic component. However, no robust genetic associations have been published thus far due largely to the known polygenic nature of these traits and insufficient sample sizes. Here, using two GWAS datasets, in which the polygenicity of gF and gC traits was previously confirmed, a gene- and pathway-based approach was undertaken with the aim of characterizing and differentiating their genetic architecture. Pathway analysis, using genes selected on the basis of relaxed criteria, revealed notable differences between these two traits. gF appeared to be characterized by genes affecting the quantity and quality of neurons and therefore neuronal efficiency, whereas long-term depression (LTD) seemed to underlie gC. Thus, this study supports the gF-gC distinction at the genetic level and identifies functional annotations and pathways worthy of further investigation.

  5. Syntheses, Crystal Structures and Fluorescent Properties of Two New Imidazolidino Schiff Base Compounds

    Institute of Scientific and Technical Information of China (English)

    FENG Yue; LIU Gang; TIAN Xiu-Mei; WANG Ji-De; WANG Wei

    2008-01-01

    Two new imidazolidino Schiff base compounds, (E)-N-((quinoxalin-2-yl)methylene)-2-(2-(quinoxalin-3-yl)imidazolidin-1-yl)ethanamine 1 and 2-(1-(2-(2-(quinoxalin-3-yl)imidazolidin-1-yl)ethyl)imidazolidin-2-yl)quinoxaline 2, have been synthesized and characterized by elemental analysis,1H NMR, IR, MS and single-crystal X-ray diffraction. Crystallographic data for 1: C22H21N7,Mr = 383.46, monoclinic, space group P21, a = 7.0036(14), b=6.9151(14), c=19.701(4)(A),β=96.57(3)°, Z = 2, V=947.9(3)(A)3, Dc = 1.344 g/cm3, F(000)=404, μ = 0.085 mm-1, Flack parameter =0(2), R = 0.0464 and wR = 0.1055; and those for 2: C24H26N8, Mr = 426.53, triclinic, space group P(1),a = 9.6680(19), b = 10.334(2), c = 11.389(2)(A),α= 104.12(3),β= 102.95(3),γ= 100.48(3)°, Z=2,V=1041.2(4)(A)3, Dc=1.361 g/cm3, F(000) = 452,μ = 0.086 mm-1, R = 0.0373 and wR = 0.1155. For the two compounds, the five-membered imidazolidine rings all adopt envelope conformation.Moreover, the title compounds show one-dimensional layered and three-dimensional supramolecular chainlike structures, respectively. Fluorescent properties of the two compounds have been investigated in the solid state at room temperature. Compound 1 exhibits strong fluorescence and thus may serve as excellent candidates of green fluorescent materials.

  6. Fission reactor flux monitors based on single-crystal CVD diamond films

    Energy Technology Data Exchange (ETDEWEB)

    Almaviva, S.; Marinelli, M.; Prestopino, G.; Tucciarone, A.; Verona, C.; Verona-Rinati, G. [Dipartimento di Ingegneria Meccanica, Universita di Roma ' ' Tor Vergata' ' , Via del Politecnico 1, 00133 Roma (Italy); INFN - Sezione Roma ' ' Tor Vergata' ' (Italy); Milani, E. [INFN - Sezione Roma ' ' Tor Vergata' ' (Italy); Angelone, M.; Lattanzi, D.; Pillon, M. [Associazione EURATOM-ENEA sulla Fusione, Via E. Fermi 45, 00144 Frascati (Roma) (Italy); Rosa, R. [Dipartimento Fusione e Presidio Nucleare ENEA C.R. Casaccia, Via Anguillarese 301, 00123 Roma (Italy)

    2007-09-15

    Diamond based thermal neutron flux monitors have been fabricated using single crystal diamond films, grown by chemical vapour deposition. A 3 {mu}m thick {sup 6}LiF layer was thermally evaporated on the detector surface as a converting material for thermal neutron monitoring via the {sup 6}Li(n, {alpha}) T nuclear reaction. The detectors were tested in a fission nuclear reactor. One of them was positioned 80 cm above the core mid-plane, where the neutron flux is 2.2 x 10{sup 9} neutrons/cm{sup 2}s at 1 MW resulting in a device count rate of about 150000 cps. Good stability and reproducibility of the device output were proved over the whole reactor power range (up to 1 MW). During the irradiation, several pulse height spectra were recorded, in which both products of the {sup 6}Li(n,{alpha})T reaction, e.g. 2.73 MeV tritium and the 2.06 MeV {alpha}, were clearly identified, thus excluding a degradation of the detector response. A comparison with a reference fission chamber monitor pointed out a limitation of the adopted readout electronics at high count rates, due to multiple pile-up processes. However, once this effect is properly accounted for, a good linearity of the diamond flux monitor response is observed as a function of the fission chamber one, as well as an excellent agreement between the temporal behaviour of the two detector response. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Gapped Surface Plasmon Polariton Waveguide Device Based on a Liquid Crystal.

    Science.gov (United States)

    Lee, Dong Hun; Lee, Myung-Hyun

    2015-10-01

    We propose a gapped surface plasmon polariton waveguide (G-SPPW) device based on a liquid crystal (LC) at a wavelength of 1.55 μm. The G-SPPW device is composed of an input 2.0-μm-wide and 5.0-μm-long insulator-metal-insulator waveguide (IMI-W), an 8-μm-long gap, and an output 2.0-μm-wide and 25.0-μm-long IMI-W. The LC is used for the gap and the 5.15-μm-thick upper and lower dielectric layers. The input surface plasmon polaritons (SPPs) propagate and jump over the gap in the G-SPPW with a coupling loss of less than ~0.68 dB. The propagation and coupling losses of the 38-μm-long G-SPPW device are varied in the range of ~0.5268 dB to ~2.6716 dB and ~0.1446 dB to ~0.6784 dB, respectively, with LC tilt angles (θ1,2) = 0°~90° at a fixed 90° twist angle. The normalized transmission of the G-SPPW device is also varied in the range from -3.351 dB to -0.6714 dB with θ1,2 = 0°~90° at a fixed 90° twist angle. The output SPP characteristics of the G-SPPW device can be properly controlled by the orientation of the LC molecules. The proposed G-SPPW device shows potential for new active plasmonic device applications. PMID:26726399

  8. Characterization of heavy oxide inorganic scintillator crystals for direct detection of fast neutrons based on inelastic scattering

    OpenAIRE

    Rusiecki, Philip R.

    2015-01-01

    Approved for public release; distribution is unlimited Heavy oxide inorganic scintillators may prove viable in the detection of fast neutrons based on the mechanism of inelastic neutron scattering. A candidate set of crystals incorporating constituents of heavy atomic mass, namely bismuth germinate (BGO), zinc tungstate (ZWO), cadmium tungstate (CWO), lead tungstate (PWO), lutetium-gadolinium orthosilicate activated with cerium (LGSO:Ce) and lutetium-aluminum garnet with cerium (LuAG:Ce), ...

  9. Charge carrier trapping in highly-ordered lyotropic chromonic liquid crystal films based on ionic perylene diimide derivatives

    OpenAIRE

    Soroka, Pavlo V.; Vakhnin, Alexander Yu; Skryshevskiy, Yuriy A; Boiko, Oleksandr P.; Anisimov, Maksim I; Slominskiy, Yuriy L; Nazarenko, Vassili G.; Genoe, Jan; Kadashchuk, Andrey

    2014-01-01

    Charge carrier trapping in thin films of lyotropic chromonic liquid crystals (LCLCs) based on ionic perylene diimide derivative and in chemically-similar neutral N,N′-dipentyl-3,4,9,10-perylene-dicarboximide (PTCDI-C5) films is investigated by thermally-stimulated luminescence (TSL) technique. The LCLC films comprise elongated molecular aggregates featuring a long-range orientational order. The obtained results provide direct evidence for the improved energetic ordering (smaller effective ene...

  10. Crystal Engineering of HIV-1 Reverse Transcriptase for structure-Based Drug Design

    Energy Technology Data Exchange (ETDEWEB)

    Bauman,J.; Das, K.; Ho, W.; Baweja, M.; Himmel, D.; Clark, A.; Oren, D.; Shatkin, A.; Arnold, E.

    2008-01-01

    HIV-1 reverse transcriptase (RT) is a primary target for anti-AIDS drugs. Structures of HIV-1 RT, usually determined at {approx}2.5-3.0 Angstroms resolution, are important for understanding enzyme function and mechanisms of drug resistance in addition to being helpful in the design of RT inhibitors. Despite hundreds of attempts, it was not possible to obtain the structure of a complex of HIV-1 RT with TMC278, a nonnucleoside RT inhibitor (NNRTI) in advanced clinical trials. A systematic and iterative protein crystal engineering approach was developed to optimize RT for obtaining crystals in complexes with TMC278 and other NNRTIs that diffract X-rays to 1.8 Angstroms resolution. Another form of engineered RT was optimized to produce a high-resolution apo-RT crystal form, reported here at 1.85 Angstroms resolution, with a distinct RT conformation. Engineered RTs were mutagenized using a new, flexible and cost effective method called methylated overlap-extension ligation independent cloning. Our analysis suggests that reducing the solvent content, increasing lattice contacts, and stabilizing the internal low-energy conformations of RT are critical for the growth of crystals that diffract to high resolution. The new RTs enable rapid crystallization and yield high-resolution structures that are useful in designing/developing new anti-AIDS drugs.

  11. Influences of ruthenium and crystallographic orientation on creep behavior of aluminized nickel-base single crystal superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Latief, F.H., E-mail: fahamsyah78@gmail.com [Department of Mechanical Engineering, Tokyo Metropolitan University, 1-1 Minami-osawa, Hachioji-shi, Tokyo 192-0397 (Japan); Kakehi, K. [Department of Mechanical Engineering, Tokyo Metropolitan University, 1-1 Minami-osawa, Hachioji-shi, Tokyo 192-0397 (Japan); An-Chou Yeh, H. [Department of Materials Science and Engineering, National TsingHua University, 101, Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan (China); Murakami, H. [Hybrid Materials Center, National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan)

    2014-01-13

    The influences of ruthenium and surface orientation on creep behavior of aluminized Ni-base single crystal superalloys were investigated by comparing two different types of NKH superalloys. The aluminized coated specimens were then subjected to creep rupture tests at a temperature of 900 °C and a stress of 392 MPa. The coating treatment resulted in a significant decrease in creep rupture lives for both superalloys. The diffusion zones between the coating and substrate led to changes in microstructure, which diminished the creep behavior of the aluminized superalloys. Because of the interdiffusion of Ru, Al and Ni, the solubility of some of the refractory elements, such as W, Re. Mo, Co and Cr decreased in the diffusion zone; the precipitation of topologically close-packed (TCP) phases was thus inevitable. In the present study, the addition of Ru increased the degree of Re and Cr supersaturation in the γ matrix. Consequently, the addition of Ru indirectly promoted the precipitation of TCP phases in aluminized Ni-base single crystal superalloys. Furthermore, the growth of TCP precipitates was greatly influenced by the specific surface orientations of the Ni-base single crystal superalloys. In conclusion, the {110} specimens showed shorter creep rupture life than the {100} specimens, this was due to the difference in the crystallographic geometry of {111}〈101〉 slip system and TCP precipitates between the two side-surface orientations of the specimens.

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

    International Nuclear Information System (INIS)

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

  13. Crystal structure determiningof 7-ADCA based on X-raypowder diffraction

    Institute of Scientific and Technical Information of China (English)

    HU Enping; CHENG Qiang; GUO Linghong; LI Hui

    2006-01-01

    Optimum resolution data of X-ray powder diffraction for 7-amino desacetoxy cephalospo- ranic acid(7-ADCA) were collected from an X' Pert Pro MPD diffractometer with the setup of 0.01°/s and 0.01° per step. Indexing to the crystal system and searching space group from the diffraction data were conducted by means of the computational crystallography method. The pilot crystal models of 7-ADCA were then refined by Rietveld method to obtain the exact three-dimensional structure. The results show that the crystal structure of 7-ADCA is monoclinic, space group P21 with unit cell dimensions a=13.50(A) b=6.01(A), c =5.91(A), α=γ=90.00°,β=101.96°, Z=2 and V =469.10(A)3. The fraction coordinate of each atom in the unit cell is well located and reported.

  14. Redetermination of Mg2B25 based on single-crystal X-ray data

    Directory of Open Access Journals (Sweden)

    Luca Bindi

    2012-06-01

    Full Text Available The crystal structure of Mg2B25, dimagnesium pentaeicosaboride, was reexamined from single-crystal X-ray diffraction data. The structural model previously reported on the basis of powder X-ray diffraction data [Giunchi et al. (2006. Solid State Sci. 8, 1202–1208] has been confirmed, although a much higher precision refinement was achieved, leading to much smaller standard uncertainties on bond lengths and refined occupancy factors. Moreover, all atoms were refined with anisotropic displacement parameters. Mg2B25 crystallizes in the β-boron structure type and is isostructural with other rhombohedral compounds of the boron-rich metal boride family. Magnesium atoms are found in interstitial sites on special positions (two with site symmetry .m, one with .2 and one with 3m, all with partial occupancies.

  15. Structure Tuning of Line-Defect Waveguides Based on Silicon-on-Insulator Photonic Crystal Slabs

    Institute of Scientific and Technical Information of China (English)

    WANG Chun-Xia; XU Xing-Sheng; XIONG Gui-Guang; HU Hai-Yang; SONG Qian; DU Wei; CHEN Hong-Da

    2007-01-01

    We present fabrication and experimental measurement of a series of photonic crystal waveguides. The complete devices consist of an injector taper down from 3 μm into a triangular-lattice air-hole single-line-defect waveguide with lattice constant from 410nm to 470nm and normalized radius 0.31. We fabricate these devices on a siliconon-insulator substrate and characterize them using a tunable laser source over a wavelength range from 1510 nm to 1640nm. A sharp attenuation at photonic crystal waveguide mode edge is observed for most structures. The edge of guided band is shifted about 30nm with the 10nm increase of the lattice constant. We obtain high-efficiency light propagation and broad flat spectrum response of the photonic crystal waveguides.

  16. Rhombohedral-to-tetragonal phase transformation and thermal depolarization in relaxor-based ferroelectric single crystal

    Science.gov (United States)

    Chang, W. S.; Lim, L. C.; Yang, P.; Tu, C.-S.

    2008-08-01

    The rhombohedral-to-tetragonal (R-T) transformation in relaxor single crystals occurs over a temperature range, manifested by the coexistence of rhombohedral (R ) and tetragonal (T) microscopic and nanotwin domains, a string of thermal current signals, and continued degradation of dielectric and electromechanical properties. Thermal current and high-resolution x-ray diffraction results suggest TRT≅100-135 °C for [001]-poled PZN-4.5%PT and 90-115 °C for [001]-poled PZN-7%PT. The "TRT" determined from the dielectric permittivity-temperature plot of poled crystals corresponds to the lower bound of TRT, which is also a good indication of the depolarization temperature (TDP) of relaxor ferroelectric single crystals above which perceptible property degradation begins.

  17. Optimization of detection system based on inorganic scintillation crystal coupled with a long lightguide

    CERN Document Server

    Globus, M; Ratner, M

    2002-01-01

    Operation characteristics of a scintillation crystal, linked with the photomultiplier by a long transparent lightguide, are considered (such detection systems are used for monitoring the seawater pollution, scintillation measurements in magnetic field, etc.). This system is optimized with respect to the refractive index of the liquid, coupling the crystal with the lightguide, and the roughness degree of the crystal surface. It is shown that the energy resolution of the system can be significantly improved by using the coupling liquid with a refractive index somewhat less than that of the lightguide (a difference of about 0.2 is optimal). Light output and especially energy resolution becomes better with an increase of the roughness degree of the reflecting surface.

  18. Surface Crystallization in Mg-Based Bulk Metallic Glass during Copper Mold Casting

    Directory of Open Access Journals (Sweden)

    Xin Wang

    2014-01-01

    Full Text Available The localized crystallization of Mg54Cu28Ag7Y11 bulk metallic glass (BMG in the injection casting process using a copper mold was investigated. It has been found that several crystalline phases were formed close to the as-cast surface but did not exist in the internal part of the BMG plate. It is abnormal that the as-cast surface is partially crystallized with higher cooling rate than that of inside. Overheating of the melt and nucleation induced by the surface of copper mold play key roles in the abnormal crystallization. It is suggested that the function of copper mold to trigger heterogeneous nucleation cannot be totally ignored, although it provides the high cooling rate for the glass formation during casting.

  19. Rapid yet accurate first principle based predictions of alkali halide crystal phases using alchemical perturbation

    CERN Document Server

    Solovyeva, Alisa

    2016-01-01

    We assess the predictive power of alchemical perturbations for estimating fundamental properties in ionic crystals. Using density functional theory we have calculated formation energies, lattice constants, and bulk moduli for all sixteen iso-valence-electronic combinations of pure pristine alkali halides involving elements $A \\in \\{$Na, K, Rb, Cs$\\}$ and $X \\in \\{$F, Cl, Br, I$\\}$. For rock salt, zincblende and cesium chloride symmetry, alchemical Hellmann-Feynman derivatives, evaluated along lattice scans of sixteen reference crystals, have been obtained for all respective 16$\\times$15 combinations of reference and predicted target crystals. Mean absolute errors (MAE) are on par with density functional theory level of accuracy for energies and bulk modulus. Predicted lattice constants are less accurate. NaCl is the best reference salt for alchemical estimates of relative energies (MAE $<$ 40 meV/atom) while alkali fluorides are the worst. By contrast, lattice constants are predicted best using NaF as a re...

  20. Optimization of the idler wavelength tunable cascaded optical parametric oscillator based on chirp-assisted aperiodically poled lithium niobate crystal

    Science.gov (United States)

    Tao, Chen; Rong, Shu; Ye, Ge; Zhuo, Chen

    2016-01-01

    We present the numerical results for the optimization of the pump-to-idler conversion efficiencies of nanosecond idler wavelength tunable cascaded optical parametric oscillators (OPO) in different wavelength tuning ranges, where the primary signals from the OPO process are recycled to enhance the pump-to-idler conversion efficiencies via the simultaneous difference frequency generation (DFG) process by monolithic aperiodically poled, magnesium oxide doped lithium niobate (APMgLN) crystals. The APMgLN crystals are designed with different chirp parameters for the DFG process to broaden their thermal acceptance bandwidths to different extents. The idler wavelength tuning of the cascaded OPO is realized by changing the temperature of the designed APMgLN crystal and the cascaded oscillation is achieved in a single pump pass singly resonant linear cavity. The pump-to-idler conversion efficiencies with respect to the pump pulse duration and ratio of OPO coefficient to DFG coefficient are calculated by numerically solving the coupled wave equations. The optimal working conditions of the tunable cascaded OPOs pumped by pulses with energies of 350 μJ and 700 μJ are compared to obtain the general rules of optimization. It is concluded that the optimization becomes the interplay between the ratio of OPO coefficient to DFG coefficient and the pump pulse duration when the idler wavelength tuning range and the pump pulse energy are fixed. Besides, higher pump pulse energy is beneficial for reaching higher optimal pump-to-idler conversion efficiency as long as the APMgLN crystal is optimized according to this pump condition. To the best of our knowledge, this is the first numerical analysis of idler wavelength tunable cascaded OPOs based on chirp-assisted APMgLN crystals. Project supported by the National Natural Science Foundation of China (Grant No. 61505236), the Innovation Program of Shanghai Institute of Technical Physics, China (Grant No. CX-2), and the Program of Shanghai

  1. 3D-Modeling of deformed halite hopper crystals: Object based image analysis and support vector machine, a first evaluation

    Science.gov (United States)

    Leitner, Christoph; Hofmann, Peter; Marschallinger, Robert

    2014-05-01

    Halite hopper crystals are thought to develop by displacive growth in unconsolidated mud (Gornitz & Schreiber, 1984). The Alpine Haselgebirge, but also e.g. the salt deposits of the Rhine graben (mined at the beginning of the 20th century), comprise hopper crystals with shapes of cuboids, parallelepipeds and rhombohedrons (Görgey, 1912). Obviously, they deformed under oriented stress, which had been tried to reconstruct with respect to the sedimentary layering (Leitner et al., 2013). In the present work, deformed halite hopper crystals embedded in mudrock were automated reconstructed. Object based image analysis (OBIA) has been used successfully in remote sensing for 2D images before. The present study represents the first time that the method was used for reconstruction of three dimensional geological objects. First, manually a reference (gold standard) was created by redrawing contours of the halite crystals on each HRXCT scanning slice. Then, for OBIA, the computer program eCognition was used. For the automated reconstruction a rule set was developed. Thereby, the strength of OBIA was to recognize all objects similar to halite hopper crystals and in particular to eliminate cracks. In a second step, all the objects unsuitable for a structural deformation analysis were dismissed using a support vector machine (SVM) (clusters, polyhalite-coated crystals and spherical halites) The SVM simultaneously drastically reduced the number of halites. From 184 OBIA-objects 67 well shaped remained, which comes close to the number of pre-selected 52 objects. To assess the accuracy of the automated reconstruction, the result before and after SVM was compared to the reference, i.e. the gold standard. State-of the art per-scene statistics were extended to a per-object statistics. Görgey R (1912) Zur Kenntnis der Kalisalzlager von Wittelsheim im Ober-Elsaß. Tschermaks Mineral Petrogr Mitt 31:339-468 Gornitz VM, Schreiber BC (1981) Displacive halite hoppers from the dead sea

  2. Tunable phononic crystals based on piezoelectric composites with 1-3 connectivity.

    Science.gov (United States)

    Croënne, Charles; Ponge, Marie-Fraise; Dubus, Bertrand; Granger, Christian; Haumesser, Lionel; Levassort, Franck; Vasseur, Jérôme O; Lordereau, Albert; Pham Thi, Mai; Hladky-Hennion, Anne-Christine

    2016-06-01

    Phononic crystals made of piezoelectric composites with 1-3 connectivity are studied theoretically and experimentally. It is shown that they present Bragg band gaps that depend on the periodic electrical boundary conditions. These structures have improved properties compared to phononic crystals composed of bulk piezoelectric elements, especially the existence of larger band gaps and the fact that they do not require severe constraints on their aspect ratios. Experimental results present an overall agreement with the theoretical predictions and clearly show that the pass bands and stop bands of the device under study are easily tunable by only changing the electrical boundary conditions applied on each piezocomposite layer. PMID:27369154

  3. Study on crystal transformation process of magnesium carbonate hydrate based on salt lake magnesium resource utilization

    OpenAIRE

    Du, Juan; Chen, Zhen; WU, Yu-Long; YANG, Ming-De

    2013-01-01

    The crystal transformation process of magnesium carbonate hydrate by the reaction of magnesium sulfate (MgSO4) with ammonium carbonate [(NH4)2CO3] was investigated. MgSO4 is one of the main magnesium resources of the Lop Nur salt lake in the Xinjiang Autonomous Region of China. Magnesium carbonate hydrates with different chemical compositions were prepared. The transformation process of the 2 crystals, MgSO4 and (NH4)2CO3, was analyzed by Raman spectroscopy, and the associated chang...

  4. Refractive index sensor based on a 1D photonic crystal in a microfluidic channel

    DEFF Research Database (Denmark)

    Rodrigues de Sousa Nunes, Pedro André; Mortensen, Asger; Kutter, Jörg Peter;

    2010-01-01

    A refractive index sensor has been fabricated in silicon oxynitride by standard UV lithography and dry etching processes. The refractive index sensor consists of a 1D photonic crystal (PhC) embedded in a microfluidic channel addressed by fiber-terminated planar waveguides. Experimental demonstrat......A refractive index sensor has been fabricated in silicon oxynitride by standard UV lithography and dry etching processes. The refractive index sensor consists of a 1D photonic crystal (PhC) embedded in a microfluidic channel addressed by fiber-terminated planar waveguides. Experimental...

  5. Iron-based composition for magnetocaloric effect (MCE) applications and method of making a single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Evans, III, Boyd Mccutchen; Kisner, Roger A.; Ludtka, Gail Mackiewicz; Ludtka, Gerard Michael; Melin, Alexander M.; Nicholson, Donald M.; Parish; , Chad M.; Rios, Orlando; Sefat, Athena S.; West, David L.; Wilgen, John B.

    2016-02-09

    A method of making a single crystal comprises heating a material comprising magnetic anisotropy to a temperature T sufficient to form a melt of the material. A magnetic field of at least about 1 Tesla is applied to the melt at the temperature T, where a magnetic free energy difference .DELTA.G.sub.m between different crystallographic axes is greater than a thermal energy kT. While applying the magnetic field, the melt is cooled at a rate of about 30.degree. C./min or higher, and the melt solidifies to form a single crystal of the material.

  6. Photonic crystal-based resonant antenna with a very high directivity

    International Nuclear Information System (INIS)

    We investigate the radiation properties of an antenna that was formed by a hybrid combination of a monopole radiation source and a cavity built around a dielectric layer-by-layer three-dimensional photonic crystal. We measured a maximum directivity of 310, and a power enhancement of 180 at the resonant frequency of the cavity. We observed that the antenna has a narrow bandwidth determined by the cavity, where the resonant frequency can be tuned within the band gap of the photonic crystal. The measured radiation patterns agree well with our theoretical results. (c) 2000 American Institute of Physics

  7. Design and analysis of single-mode tellurite photonic crystal fibers for stimulated Brillouin scattering based slow-light generation.

    Science.gov (United States)

    Jain, Varsha; Sharma, Shubham; Saini, Than Singh; Kumar, Ajeet; Sinha, Ravindra Kumar

    2016-09-01

    We theoretically examine two designs of single-mode (i) Er-doped tellurite and (ii) undoped tellurite photonic crystal fiber (PCF) for generation of slow light with tunable features based on stimulated Brillouin scattering. We obtained (i) Brillouin gain up to 91 dB and time delay of ∼145  ns at maximum allowable pump power of ∼775  mW in a 2 m Er-doped tellurite PCF and (ii) Brillouin gain up to ∼88  dB and time delay of ∼154  ns at maximum allowable pump power ∼21  mW in a 100 m undoped tellurite photonic crystal fiber. Simulated results clearly indicate that the doped tellurite PCF with Er enhances the maximum allowable pump power and comparable time delay can be obtained even with reduced photonic crystal fiber length. We believe that the carried out examination and simulation have potential impact on design and development of slow-light-based photonic devices applicable in telecommunication systems, enhancement of optical forces, and quantum computing. PMID:27607250

  8. Synthesis, crystal structures, spectroscopic characterization and in vitro antidiabetic studies of new Schiff base Copper(II) complexes

    Indian Academy of Sciences (India)

    SUNDARAMURTHY SANTHA LAKSHMI; KANNAPPAN GEETHA; M GAYATHRI; GANESH SHANMUGAM

    2016-07-01

    Two new Schiff base copper(II) complexes, [CuL¹(tmen)] (1) and [Cu₂L₂² (tmen)] (2) {where, H₂L¹ = N-(salicylidene)-L-valine, H₂L² = N-(3,5-dichlorosalicylidene)-L-valine and tmen = N,N,N',N'- tetramethylethylene-1,2-diamine} have been synthesized and characterized by molar conductance, elemental analyses, VSM-RT, UV-Vis, FTIR, EPR, and CD spectra. Both the complexes were structurally characterized by single crystal XRD. The crystal structure of complex 1 displays a distorted square pyramidal geometry in which Schiff base is coordinated to the Cu(II) ion via ONO-donor in the axial mode, whereas, the chelating diamine displays axial and equatorial mode of binding via NN-donor atoms. The crystal structure of the complex 2 reveals a syn-anti mode of carboxylate bridged dinuclear complex, in which, the coordination geometry around Cu(1) is square pyramid and distorted square planar around Cu(2). The target complexes were screened for in vitro antidiabetic activity. Both the complexes showed good inhibitory activity for α-amylase and α-glucosidase.

  9. Small organic molecules detection based on aptamer-modified gold nanoparticles-enhanced quartz crystal microbalance with dissipation biosensor.

    Science.gov (United States)

    Zheng, Bin; Cheng, Sheng; Liu, Wei; Lam, Michael Hon-Wah; Liang, Haojun

    2013-07-15

    Small molecules are difficult to detect by the conventional quartz crystal microbalance with dissipation (QCM-D) technique directly because the changes in frequency resulting from the binding processes of small biomolecules are often small. In the current study, an aptamer-based gold nanoparticles (AuNPs)-enhanced sensing strategy for detection of small molecules was developed. The QCM crystal was first modified with a layer of thiolated linker DNA, which can be partly base-paired with the detection part containing the adenosine aptamer sequence. In the presence of adenosine, the aptamer bound with adenosine and folded to the complex structure, which precluded the reporter part carrying AuNPs to combine with the random coiled detection part. Therefore, the lower the concentration of adenosine, the more AuNPs combined to the crystal. The resulting aptasensor showed a linear response to the increase of the adenosine concentration in the range of 0-2 μM with a linear correlation of r=0.99148 and a detection limit of 65 nM. Moreover, the aptasensor exhibited several excellent characteristics such as high sensitivity, selectivity, good stability, and reproducibility.

  10. Lecithin based lamellar liquid crystals as a physiologically acceptable dermal delivery system for ascorbyl palmitate.

    Science.gov (United States)

    Gosenca, Mirjam; Bešter-Rogač, Marija; Gašperlin, Mirjana

    2013-09-27

    Liquid crystalline systems with a lamellar structure have been extensively studied as dermal delivery systems. Ascorbyl palmitate (AP) is one of the most studied and used ascorbic acid derivatives and is employed as an antioxidant to prevent skin aging. The aim of this study was to develop and characterize skin-compliant dermal delivery systems with a liquid crystalline structure for AP. First, a pseudoternary phase diagram was constructed using Tween 80/lecithin/isopropyl myristate/water at a Tween 80/lecithin mass ratio of 1/1, and the region of lamellar liquid crystals was identified. Second, selected unloaded and AP-loaded lamellar liquid crystal systems were physicochemically characterized with polarizing optical microscopy, small-angle X-ray scattering, differential scanning calorimetry, and rheology techniques. The interlayer spacing and rheological parameters differ regarding quantitative composition, whereas the microstructure of the lamellar phase was affected by the AP incorporation, resulting either in additional micellar structures (at 25 and 32 °C) or being completely destroyed at higher temperature (37°C). After this, the study was oriented towards in vitro cytotoxicity evaluation of lamellar liquid crystal systems on a keratinocyte cell line. The results suggest that the lamellar liquid crystals that were developed could be used as a physiologically acceptable dermal delivery system. PMID:23643736

  11. A Highly Linear All Optical Gate Based on Coupled Photonic Crystal Cavities

    OpenAIRE

    Moille, Gregory; De Rossi, Alfredo; Lehoucq, Gaelle; Martin, Aude; Bramerie, Laurent; Gay, Mathilde; Combrie, Sylvain

    2014-01-01

    International audience A photonic crystal molecule is used as an all-optical gate to perform sampling of microwave signals. We demonstrate a very linear operation over a 50dB still with a 1.2mW power consumption.

  12. Band gap and refractive index tunability in thallium based layered mixed crystals

    Energy Technology Data Exchange (ETDEWEB)

    Gasanly, N. M., E-mail: nizami@metu.edu.tr [Department of Physics, Middle East Technical University, Ankara 06800 (Turkey); Virtual International Scientific Research Centre, Baku State University, Baku 1148 (Azerbaijan)

    2015-07-21

    Compositional variation of the band gap energy and refractive index of TlMeX{sub 2}-type (Me = Ga or In and X = S or Se) layered mixed crystals have been studied by the transmission and reflection measurements in the wavelength range of 400–1100 nm. The analysis of absorption data of TlGa{sub 1-x}In{sub x}Se{sub 2}, TlGa(S{sub 1−x}Se{sub x}){sub 2}, TlGa{sub 1−x}In{sub x}S{sub 2}, and TlIn(Se{sub 1−x}S{sub x}){sub 2} mixed crystals revealed the presence of both optical indirect and direct transitions. It was found that the energy band gaps of mixed crystals decrease at the replacing of gallium atoms by indium and of sulfur atoms by selenium ones. Through the similar replacing of atoms (smaller atoms by larger ones) in the studied mixed crystals, the refractive index shows the quite opposite behavior.

  13. Spatial mode effects in a cavity-EIT based quantum memory with ion Coulomb crystals

    DEFF Research Database (Denmark)

    Zangenberg, Kasper Rothe; Dantan, Aurelien Romain; Drewsen, Michael

    2012-01-01

    Quantum storage and retrieval of light in ion Coulomb crystals using cavity electromagnetically induced transparency are investigated theoretically. It is found that when both the control and the probe fields are coupled to the same spatial cavity mode, their transverse mode profile affects the...

  14. Refractive Index Measurement within a Photonic Crystal Fibre Based on Short Wavelength Diffraction

    Directory of Open Access Journals (Sweden)

    Nathaniel Groothoff

    2007-10-01

    Full Text Available A new class of refractive index sensors using solid core photonic crystal fibres isdemonstrated. Coherent scattering at the cladding lattice is used to optically characterizematerials inserted into the fibre holes. The liquid to solid phase transition of water uponfreezing to ice 1h is characterized by determining the refractive index.

  15. Nanoassembly of Polydisperse Photonic Crystals based on Binary and Ternary Polymer Opal Alloys

    CERN Document Server

    Zhao, Qibin; Schafer, Christian; Spahn, Peter; Gallei, Markus; Herrmann, Lars; Petukhov, Andrei; Baumberg, Jeremy J

    2016-01-01

    Ordered binary and ternary photonic crystals, composed of different sized polymer-composite spheres with diameter ratios up to 120%, are generated using bending induced oscillatory shearing (BIOS). This viscoelastic system creates polydisperse equilibrium structures, producing mixed opaline colored films with greatly reduced requirements for particle monodispersity, and very different sphere size ratios, compared to other methods of nano-assembly.

  16. Security devices based on liquid crystals doped with a colour dye

    Science.gov (United States)

    Carrasco-Vela, C.; Quintana, X.; Otón, E.; Geday, M. A.; Otón, J. M.

    2011-12-01

    Liquid crystal properties make them useful for the development of security devices in applications of authentication and detection of fakes. Induced orientation of liquid crystal molecules and birefringence are the two main properties used in security devices. Employing liquid crystal and dichroic colorants, we have developed devices that show, with the aid of a polarizer, multiple images on each side of the device. Rubbed polyimide is used as alignment layer on each substrate of the LC cell. By rubbing the polyimide in different directions in each substrate it is possible to create any kind of symbols, drawings or motifs with a greyscale; the more complex the created device is, the more difficult is to fake it. To identify the motifs it is necessary to use polarized light. Depending on whether the polarizer is located in front of the LC cell or behind it, different motifs from one or the other substrate are shown. The effect arises from the dopant colour dye added to the liquid crystal, the induced orientation and the twist structure. In practice, a grazing reflection on a dielectric surface is polarized enough to see the effect. Any LC flat panel display can obviously be used as backlight as well.

  17. Photonic crystal fiber based evanescent-wave sensor for detection of biomolecules in aqueous solutions

    DEFF Research Database (Denmark)

    Jensen, Jesper Bo Damm; Pedersen, Lars H.; Hoiby, Poul E.;

    2004-01-01

    We demonstrate highly efficient evanescent-wave detection of fluorophore-labeled biomolecules in aqueous solutions positioned in the air holes of the microstructured part of a photonic crystal fiber. The air-suspended silica structures located between three neighboring air holes in the cladding...

  18. Visible light dynamical diffraction in a 1-D photonic crystal-based interferometer with an extremely thin spacer layer

    Science.gov (United States)

    Prudnikov, I. R.

    2016-01-01

    Properties of light diffraction in a Fabry-Pérot-like interferometer composed of two 1-D photonic crystals and a nanometer-thick spacer layer are analytically investigated. It is shown that the resonant enhancement of light wave intensity in such a layer is possible because of light dynamical diffraction from the photonic crystals of the interferometer. Numerical simulations of (i) light reflectivity and transmittance curves of the interferometer having an ultra-thin spacer layer (its thickness changes from less than 1 nm to about 10 nm) and (ii) the resonant distribution of the light wave intensity in the vicinity of the layer are performed. Based on the numerical simulations, potentialities for the determination of the structural parameters (e.g., thicknesses and refraction indexes) of ultra-thin spacer films are discussed. A difference is found to appear in resonant intensity enhancements inside the ultra-thin spacer layers between s- and p-polarized light waves.

  19. Refractive index sensing performance analysis of photonic crystal Mach-Zehnder interferometer based on BP neural network optimization

    Science.gov (United States)

    Chen, Ying; Liu, Teng; Wang, Wenyue; Zhu, Qiguang; Bi, Weihong

    2015-04-01

    According to the band gap and photon localization characteristics, the single-arm notching and the double-arm notching Mach-Zehnder interferometer (MZI) structures based on 2D triangular lattice air hole-typed photonic crystal waveguide are proposed. The back-propagation (BP) neural network is introduced to optimize the structural parameters of the photonic crystal MZI structure, which results in the normalized transmission peak increasing from 85.3% to 97.1%. The sensitivity performances of the two structures are compared and analyzed using the Salmonella solution samples with different concentrations in the numerical simulation. The results show that the sensitivity of the double-arm notching structure is 4583 nm/RIU, which is about 6.4 times of the single-arm notching structure, which can provide some references for the optimization of the photonic devices and the design of high-sensitivity biosensors.

  20. A sub-40 mHz linewidth laser based on a silicon single-crystal optical cavity

    CERN Document Server

    Kessler, T; Grebing, C; Legero, T; Sterr, U; Riehle, F; Martin, M J; Chen, L; Ye, J

    2011-01-01

    State-of-the-art optical oscillators based on lasers frequency stabilized to high finesse optical cavities are limited by thermal noise that causes fluctuations of the cavity length. Thermal noise represents a fundamental limit to the stability of an optical interferometer and plays a key role in modern optical metrology. We demonstrate a novel design to reduce the thermal noise limit for optical cavities by an order of magnitude and present an experimental realization of this new cavity system, demonstrating the most stable oscillator of any kind to date. The cavity spacer and the mirror substrates are both constructed from single crystal silicon and operated at 124 K where the silicon thermal expansion coefficient is zero and the silicon mechanical loss is small. The cavity is supported in a vibration-insensitive configuration, which, together with the superior stiffness of silicon crystal, reduces the vibration related noise. With rigorous analysis of heterodyne beat signals among three independent stable ...

  1. A review on the synthesis, crystal growth, structure and physical properties of rare earth based quaternary intermetallic compounds

    Science.gov (United States)

    Mumbaraddi, Dundappa; Sarkar, Sumanta; Peter, Sebastian C.

    2016-04-01

    This review highlights the synthesis and crystal growth of quaternary intermetallic compounds based on rare earth metals. In the first part of this review, we highlight briefly about intermetallics and their versatile properties in comparison to the constituent elements. In the next part, we have discussed about various synthesis techniques with more focus on the metal flux technique towards the well shaped crystal growth of novel compounds. In the subsequent parts, several disordered quaternary compounds have been reviewed and then outlined most known ordered quaternary compounds with their complex structure. A special attention has been given to the ordered compounds with structural description and relation to the parent binary and ternary compounds. The importance of electronic and structural feature is highlighted as the key roles in designing these materials for emerging applications.

  2. Ultracompact transverse magnetic mode-pass filter based on one-dimensional photonic crystals with subwavelength structures.

    Science.gov (United States)

    Kim, Dong Wook; Lee, Moon Hyeok; Kim, Yudeuk; Kim, Kyong Hon

    2016-09-19

    We propose and experimentally demonstrate an ultracompact transverse magnetic (TM) mode pass filter based on a rectangularly-shaped one-dimensional (1-D) photonic crystal silicon waveguide with an extremely high polarization extinction ratio (PER) of >30 dB and a low insertion loss (IL) of ~1 dB. The device structure of the TM mode-pass filter is numerically simulated using a three-dimensional (3-D) finite difference time domain (FDTD) method. The proposed device supports its fundamental TM mode only, whereas the transverse electric (TE) mode is reflected by the 1-D photonic crystals (PhCs). The measured PER of the fabricated TM mode-pass filter is ~34 dB, and the IL is about 1 dB. The entire device length is about 4 μm. Our simulation results predict that the device bandwidth of 30 dB PER is about 200 nm. PMID:27661894

  3. A new design procedure for all-optical photonic crystal logic gates and functions based on threshold logic

    Science.gov (United States)

    Sharifi, Hojjat; Hamidi, Seyyedeh Mehri; Navi, Keivan

    2016-07-01

    In this paper, a general method is proposed to design all-optical photonic crystal logic gates and functions based on threshold logic concept that have regular pattern in inputs. In our proposed structure, a photonic crystal junction is cascaded by a threshold power level detector. Additionally, a novel mechanism is introduced to shift the threshold power level for designing different logic gates and functions. The finite difference time domain and plane wave expansion methods are used to evaluate the proposed structures. The proposed gates and functions occupy an area less than 150 μm2 and also, the maximum power required for the switching mechanism is 15 μW. The inputs and output in the mentioned gates and functions are homogeneous and they can operate with a bit rate of about 500 Gbits/s.

  4. Optical filters using Cantor quasi-periodic one dimensional photonic crystal based on Si/SiO2

    Science.gov (United States)

    Sahel, S.; Amri, R.; Bouaziz, L.; Gamra, D.; Lejeune, M.; Benlahsen, M.; Zellama, K.; Bouchriha, H.

    2016-09-01

    Quasi-periodic one-dimensional Cantor photonic crystals are elaborated by depositing alternating silicon and silica Si/SiO2 layers by radiofrequency magnetron sputtering technique with cold plasma. Transmittance and reflectance spectra of these quasi crystals exhibit a large photonic band gap in the infrared range at normal incidence which is well reproduced by a theoretical model based on the transfer matrix method. The obtained wide photonic band gap reveals the existence of permitted modes depending on the nature and characteristics of the built in system which can constitute optical windows. This effect can be a good alternative for the design of flexible filters used in many areas of applications such as telecommunication and optoelectronic devices.

  5. Amplified spontaneous emission lifetime based on the different phase matching modes in BaAlBO3F2 crystal

    International Nuclear Information System (INIS)

    Amplified spontaneous emission lifetime (ASEL) distribution characteristics of the new BaAlBO3F2 (BABF) crystal have been calculated via the equations of emitted light intensity and amplified signal intensity gain. The ASEL distribution was calculated and discussed for three types of injection into the BABF crystal based on an optical parametric amplifier. We found ASEL was first distributed mainly in an ellipsoid and then in a torus with the increase of the pump phase matching angle when a monochromatic signal is injected. For the polychromatic signal pulse injection, ASEL is changed from a scattered distribution to a concentrated distribution. For the broadband pump, the ASEL distribution range is greatly expanded because of the increasing phase matching range

  6. Synthesis, crystal structure and spectral characteristics of highly fluorescent chalcone-based coumarin in solution and in polymer matrix

    Science.gov (United States)

    Ghouili, Afef; Dusek, Michal; Petricek, Vaclav; Ayed, Taïcir Ben; Hassen, Rached Ben

    2014-02-01

    A new coumarin chalcone 3-((2E)-3-(2-hydroxyphenyl) prop-2-enoyl)-4-hydroxy-2(H)-chromen-2-one was synthesized using the Claisen Schmidt reaction by the condensation of 3-acetyl-4-hydroxycoumarin and 2-hydroxybenzaldehyde using a mild organic base. This novel compound was characterized by 1H NMR, FT-IR and UV-vis spectroscopy. Single crystal X-ray diffraction investigation at low temperature (T=120 K) shows that this compound exhibits an intramolecular O3-H…O hydrogen bond, the coumarin ring and the phenyl group are nearly coplanar and the crystal packing is stabilized by intermolecular O3-H…O contacts and π-π stacking interactions. This ortho-hydroxyphenyl-4-hydroxycoumarin chalcone exhibits a strong blue-green emission under visible light excitation at 470 nm. The fluorescence behaviors of this compound doped in poly(methyl methacrylate) (PMMA) were investigated.

  7. Crystallization Kinetics and Mechanism of CaO-Al2O3-Based Mold Flux for Casting High-Aluminum TRIP Steels

    Science.gov (United States)

    Shi, Cheng-Bin; Seo, Myung-Duk; Wang, Hui; Cho, Jung-Wook; Kim, Seon-Hyo

    2015-02-01

    Non-isothermal crystallization of the newly developed lime-alumina-based mold fluxes was investigated using differential scanning calorimetry. The crystallization kinetic parameters were determined by Ozawa equation, the combined Avrami-Ozawa equation, and the differential iso-conversional method of Friedman. It was found that Ozawa method failed to describe the non-isothermal crystallization behavior of the mold fluxes. The Avrami exponent determined by the combined Avrami-Ozawa equation indicates that the crystallization of cuspidine occurs through bulk nucleation and reaction-controlled three-dimensional growth, and then transforms to reaction-controlled two-dimensional growth at the crystallization later stage in lime-alumina-based mold fluxes with higher B2O3 content. For the mold fluxes with lower B2O3 content (10.8 mass pct), the crystallization of cuspidine is bulk nucleation and reaction-controlled two-dimensional growth at the crystallization primary stage followed by a diffusion-controlled two-dimensional growth process. The crystallization of CaF2 in mold flux originates from bulk nucleation and diffusion-controlled three-dimensional growth, which then transforms to two-dimensional growth. FE-SEM observations support these kinetic analysis results. The effective activation energy for cuspidine crystallization in the mold flux with higher B2O3 and Na2O contents increases as the crystallization progresses, and then decreases at the relative degree of crystallinity greater than 60 pct. The transition point of this trend approximately corresponds to the relative degree of crystallinity at which the crystallization mode of cuspidine transforms. For the mold fluxes with lower B2O3 and Na2O contents, the effective activation energy for cuspidine formation varies monotonically with the increase in the relative degree of crystallinity.

  8. Design and Performance Evaluation of Optical Ethernet Switching Architecture with Liquid Crystal on Silicon-Based Beam-Steering Technology

    Science.gov (United States)

    Cheng, Yuh-Jiuh; Chou, H.-H.; Shiau, Yhi; Cheng, Shu-Ying

    2016-07-01

    A non-blocking optical Ethernet switching architecture with liquid crystal on a silicon-based beam-steering switch and optical output buffer strategies are proposed. For preserving service packet sequencing and fairness of routing sequence, priority and round-robin algorithms are adopted at the optical output buffer in this research. Four methods were used to implement tunable fiber delay modules for the optical output buffers to handle Ethernet packets with variable bit-rates. The results reported are based on the simulations performed to evaluate the proposed switching architecture with traffic analysis under a traffic model captured from a real-core network.

  9. Nanoscale characterization of local structures and defects in photonic crystals using synchrotron-based transmission soft X-ray microscopy

    OpenAIRE

    Hyun Woo Nho; Yogesh Kalegowda; Hyun-Joon Shin; Tae Hyun Yoon

    2016-01-01

    For the structural characterization of the polystyrene (PS)-based photonic crystals (PCs), fast and direct imaging capabilities of full field transmission X-ray microscopy (TXM) were demonstrated at soft X-ray energy. PS-based PCs were prepared on an O2-plasma treated Si3N4 window and their local structures and defects were investigated using this label-free TXM technique with an image acquisition speed of ~10 sec/frame and marginal radiation damage. Micro-domains of face-centered cubic (FCC ...

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

    International Nuclear Information System (INIS)

    CMSX-4 is a recently developed rhenium containing single crystal nickel-based superalloy. This alloy has potential applications in many critical high-temperature applications such as turbine blades, rotors, nuclear reactors, etc. The fatigue crack growth rate and the fatigue threshold data of this material is extremely important for accurate life prediction, as well as failure safe design, at elevated temperatures. In this paper, the fatigue crack growth behavior of CMSX-4 has been studied at 650 C. The investigation also examined the influence of γ' precipitates (size and distribution) on the near-threshold fatigue crack growth rate and the fatigue threshold. The influence of load ratio on the fatigue crack growth rate and the fatigue threshold was also examined. Detailed fractographic studies were carried out to determine the crack growth mechanism in fatigue in the threshold region. Compact tension specimens were prepared from the single crystal nickel-based superalloy CMSX-4 with [001] orientation as the tensile loading axis direction. These specimens were given three different heat treatments to produce three different γ' precipitate sizes and distributions. Fatigue crack growth behavior of these specimens was studied at 650 C in air. The results of the present investigation indicate that the near-threshold fatigue crack growth rate decreases and that the fatigue threshold increases with an increase in the γ' precipitate size at 650 C. The fatigue threshold decreased linearly with an increase in load ratio. Fractographs at 650 C show a stage 2 type of crack growth along {100} type of crystal planes in the threshold region, and along {111} type of crystal planes in the high ΔK region

  11. A new approach to polarimetric measurements based on birefringent crystals and diode lasers

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Lívia Paulia Dias; Rohwedder, Jarbas José Rodrigues [Chemistry Institute, Department of Analytical Chemistry, UNICAMP, Caixa Postal 6154, CEP: 13087-971 Campinas, SP (Brazil); Pasquini, Celio, E-mail: pasquini@iqm.unicamp.br [Chemistry Institute, Department of Analytical Chemistry, UNICAMP, Caixa Postal 6154, CEP: 13087-971 Campinas, SP (Brazil)

    2013-04-10

    Highlights: ► New approach to polarimetric measurements is evaluated. ► A robust, with no mechanical moving parts polarimeter is presented. ► The performance of the instrument was evaluated for saccharimetric measurements. ► The uncertainty of the instrument was evaluated as a function of the measured angle. ► Polarimeter allow the use of low cost lasers while obtaining precision as good as 0.003°. -- Abstract: A new polarimetric instrument and measurement method is described based on the use of diode lasers as radiation source (532, 650 and 1064 nm) and birefringent prisms, such as Glan-Laser and Wollaston, as analyzers. The laser radiation is passed through a dichroic polarizer film for further orientation of its polarization plane at 45° in relation to the polarization plane of the analyzer. The polarized beam, oriented in that way, passes the sample cell, impinges the prism surface, and the intensities of the two emerged beams are detected by two twin silicon detectors. Ideally, in the absence of any optically active substances, the crystals produces two orthogonally polarized refracted beams of equal intensity. In the presence of an optically active substance, the arctangent of the square root of the beam intensities ratio is equal to the new polarization angle (β) of the laser beam. The rotation angle imposed for any optically active substance present in the sample cell is then given by: α = (45 – β)°. Because the rotation is obtained by the ratio of the intensities of two beams, it is independent of the laser intensity, which can vary up to ±15% with no significant effect on the accuracy of the polarimetric measurement. The instrument has been evaluated for measurement of optically active substances such as sucrose and fructose. The instrument employs low cost components, is capable of attaining a repeatability of ±0.003° and can measure the rotation angle, over a ±45° range, in less than 2 s. Because it does not present any moving

  12. Crystal Growth, Characterization and Fabrication of Cadmium Zinc Telluride-based Nuclear Detectors

    Science.gov (United States)

    Krishna, Ramesh M.

    In today's world, nuclear radiation is seeing more and more use by humanity as time goes on. Nuclear power plants are being built to supply humanity's energy needs, nuclear medical imaging is becoming more popular for diagnosing cancer and other diseases, and control of weapons-grade nuclear materials is becoming more and more important for national security. All of these needs require high-performance nuclear radiation detectors which can accurately measure the type and amount of radiation being used. However, most current radiation detection materials available commercially require extensive cooling, or simply do not function adequately for high-energy gamma-ray emitting nuclear materials such as uranium and plutonium. One of the most promising semiconductor materials being considered to create a convenient, field-deployable nuclear detector is cadmium zinc telluride (CdZnTe, or CZT). CZT is a ternary semiconductor compound which can detect high-energy gamma-rays at room temperature. It offers high resistivity (≥ 1010 O-cm), a high band gap (1.55 eV), and good electron transport properties, all of which are required for a nuclear radiation detector. However, one significant issue with CZT is that there is considerable difficulty in growing large, homogeneous, defect-free single crystals of CZT. This significantly increases the cost of producing CZT detectors, making CZT less than ideal for mass-production. Furthermore, CZT suffers from poor hole transport properties, which creates significant problems when using it as a high-energy gamma-ray detector. In this dissertation, a comprehensive investigation is undertaken using a successful growth method for CZT developed at the University of South Carolina. This method, called the solvent-growth technique, reduces the complexity required to grow detector-grade CZT single crystals. It utilizes a lower growth temperature than traditional growth methods by using Te as a solvent, while maintaining the advantages of

  13. 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)

    2015-09-01

    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.

  14. A micromotor based on polymer single crystals and nanoparticles: toward functional versatility

    Science.gov (United States)

    Liu, Mei; Liu, Limei; Gao, Wenlong; Su, Miaoda; Ge, Ya; Shi, Lili; Zhang, Hui; Dong, Bin; Li, Christopher Y.

    2014-07-01

    We report a multifunctional micromotor fabricated by the self-assembly technique using multifunctional materials, i.e. polymer single crystals and nanoparticles, as basic building blocks. Not only can this micromotor achieve autonomous and directed movement, it also possesses unprecedented functions, including enzymatic degradation-induced micromotor disassembly, sustained release and molecular detection.We report a multifunctional micromotor fabricated by the self-assembly technique using multifunctional materials, i.e. polymer single crystals and nanoparticles, as basic building blocks. Not only can this micromotor achieve autonomous and directed movement, it also possesses unprecedented functions, including enzymatic degradation-induced micromotor disassembly, sustained release and molecular detection. Electronic supplementary information (ESI) available: Experimental section, Fig. S1-S8 and Video S1-S4. See DOI: 10.1039/c4nr02593h

  15. 1.55- μm supercontinuum based on dispersion-flattened photonic crystal fiber

    Science.gov (United States)

    Zhang, Xia; Xu, Yong-Zhao; Huang, Yong-Qing; Ren, Xiao-Min

    2007-09-01

    A dispersion-flattened photonic crystal fiber with normal dispersion is designed for generating flat wideband supercontinuum, and the supercontinuum generation in this fiber is numerically analyzed. The results show that by appropriately designing the photonic crystal fiber, it can achieve flattened dispersion in the normal dispersion region. It is found that a fiber characterized by a flattened dispersion with a small normal dispersion is suitable for a flat wideband supercontinuum generation. In the process of spectral broadening, self-phase modulation effect plays a dominant role. By filtering the supercontinuum, pulses with different central wavelength over a wide spectral range can be obtained. The pulse width is determined by the bandwidth of the filter.

  16. Optical control of light propagation in photonic crystal based on electromagnetically induced transparency

    Science.gov (United States)

    Dan, Wang; Jin-Ze, Wu; Jun-Xiang, Zhang

    2016-06-01

    A kind of photonic crystal structure with modulation of the refractive index is investigated both experimentally and theoretically for exploiting electromagnetically induced transparency (EIT). The combination of EIT with periodically modulated refractive index medium gives rise to high efficiency reflection as well as forbidden transmission in a three-level atomic system coupled by standing wave. We show an accurate theoretical simulation via transfer-matrix theory, automatically accounting for multilayer reflections, thus fully demonstrate the existence of photonic crystal structure in atomic vapor. Project supported by the National Natural Science Foundation of China (Grant No. 11574188) and the Project for Excellent Research Team of the National Natural Science Foundation of China (Grant No. 61121064).

  17. Nanophotonic coherent light-matter interfaces based on rare-earth-doped crystals

    CERN Document Server

    Zhong, Tian; Miyazono, Evan; Faraon, Andrei

    2015-01-01

    Quantum light-matter interfaces (QLMIs) connecting stationary qubits to photons will enable optical networks for quantum communications, precise global time keeping, photon switching, and studies of fundamental physics. Rare-earth-ion (REI) doped crystals are state-of-the-art materials for optical quantum memories and quantum transducers between optical photons, microwave photons and spin waves. Here we demonstrate coupling of an ensemble of neodymium REIs to photonic nano-cavities fabricated in the yttrium orthosilicate host crystal. Cavity quantum electrodynamics effects including Purcell enhancement (F=42) and dipole-induced transparency are observed on the highly coherent 4I9/2-4F3/2 optical transition. Fluctuations in the cavity transmission due to statistical fine structure of the atomic density are measured, indicating operation at the quantum level. Coherent optical control of cavity-coupled REIs is performed via photon echoes. Long optical coherence times (T2~100 microseconds) and small inhomogeneous...

  18. Magneto-tunable one-dimensional graphene-based photonic crystal

    Energy Technology Data Exchange (ETDEWEB)

    Jahani, D., E-mail: dariush110@gmail.com; Soltani-Vala, A., E-mail: asoltani@tabrizu.ac.ir; Barvestani, J.; Hajian, H. [Department of Solid State Physics, Faculty of Physics, University of Tabriz, Tabriz (Iran, Islamic Republic of)

    2014-04-21

    We investigate the effect of a perpendicular static magnetic field on the optical bandgap of a one-dimensional (1D) graphene-dielectric photonic crystal in order to examine the possibility of reaching a rich tunable photonic bandgap. The solution of the wave equation in the presence of the anisotropic Hall situation suggests two decoupled circularly polarized wave each exhibiting different degrees of bandgap tunability. It is also numerically demonstrated that applying different values of field intensity lead to perceptible changes in photonic bandgap of such a structure. Finally, the effect of opening a finite electronic gap in the spectrum of graphene on the optical dispersion solution of such a 1D photonic crystal is reported. It is shown that increasing the value of the electronic gap results in the shrinkage of the associated photonic bandgaps.

  19. Deep-blue supercontinuum light sources based on tapered photonic crystal bres

    DEFF Research Database (Denmark)

    Sørensen, Simon Toft

    in the deep-blue by optimising the fibre structure. To this end, we fabricate the first single-mode high air-fill fraction photonic crystal fibre for blue-extended supercontinuum sources. The mechanisms of supercontinuum broadening are highly sensitive to noise, and the inherent shot-to-shot variations...... of the noise across the spectrum. We further investigate the possibilities of reducing the spectral noise by modulating the pump with a weak seed, which makes the broadening dynamics increasingly deterministic rather than driven by noisy modulation instability. Particular attention is paid to the commercially...... relevant high power regime. Finally, we examine passive noise reduction in photonic crystal fibres with longitudinally varying air hole structures....

  20. Hydrothermal Synthesis, Crystal Structure and Properties of Inorganic-Organic Hybrid Materials Based on Diphosphopentamolybdate

    Institute of Scientific and Technical Information of China (English)

    JIN Surong; ZHANG Lianmeng; LIU Shizhong; LUO Bo; MENG Xianggao

    2008-01-01

    The compound of diphosphopentamolybdate {[Cu(en) (Hen)]2[P2Mo5O23]}·3H2O [en=ethylenediamine] had been obtained from the hydrothermal method and characterized by single crystal X-ray diffraction, elemental analysis, FT-IR, and thermogravimetric analysis. The structure consist of [P2Mo5O23]6- clusters anions, complex [Cu(en) (Hen)]3+ cations and crystallization water molecules, which are held together to a two-dimensional framework. The most interesting feature of the compound is that two nitrogen atoms are both coordinated with Cu (Ⅱ) in one ethylenediamine molecule, for the other ethylenediamine molecule, only one nitrogen atom is towards Cu (Ⅱ) and the other nitrogen atom is protonated and formed Hen+.

  1. Photoinduced reversible switching of porosity in molecular crystals based on star-shaped azobenzene tetramers.

    Science.gov (United States)

    Baroncini, Massimo; d'Agostino, Simone; Bergamini, Giacomo; Ceroni, Paola; Comotti, Angiolina; Sozzani, Piero; Bassanetti, Irene; Grepioni, Fabrizia; Hernandez, Taylor M; Silvi, Serena; Venturi, Margherita; Credi, Alberto

    2015-08-01

    The development of solid materials that can be reversibly interconverted by light between forms with different physico-chemical properties is of great interest for separation, catalysis, optoelectronics, holography, mechanical actuation and solar energy conversion. Here, we describe a series of shape-persistent azobenzene tetramers that form porous molecular crystals in their E-configuration, the porosity of which can be tuned by changing the peripheral substituents on the molecule. Efficient E→Z photoisomerization of the azobenzene units takes place in the solid state and converts the crystals into a non-porous amorphous melt phase. Crystallinity and porosity are restored upon Z→E isomerization promoted by visible light irradiation or heating. We demonstrate that the photoisomerization enables reversible on/off switching of optical properties such as birefringence as well as the capture of CO2 from the gas phase. The linear design, structural versatility and synthetic accessibility make this new family of materials potentially interesting for technological applications.

  2. Production and crystallization of a panel of structure-based mutants of the human myelin peripheral membrane protein P2

    International Nuclear Information System (INIS)

    The myelin protein P2 is a peripheral membrane protein functional in lipid bilayer binding and stacking. In order to study the fine details of P2 structure and function, 14 point mutants of human P2 were generated and crystallized; a total of eight different crystal forms were obtained, some of which diffracted to atomic resolution. The myelin sheath is a multilayered membrane that surrounds and insulates axons in the nervous system. One of the proteins specific to the peripheral nerve myelin is P2, a protein that is able to stack lipid bilayers. With the goal of obtaining detailed information on the structure–function relationship of P2, 14 structure-based mutated variants of human P2 were generated and produced. The mutants were designed to potentially affect the binding of lipid bilayers by P2. All mutated variants were also crystallized and preliminary crystallographic data are presented. The structural data from the mutants will be combined with diverse functional assays in order to elucidate the fine details of P2 function at the molecular level

  3. High-power picosecond 355 nm laser based on La₂CaB₁₀O₁₉ crystal.

    Science.gov (United States)

    Li, Kai; Zhang, Ling; Xu, Degang; Zhang, Guochun; Yu, Haijuan; Wang, Yuye; Shan, Faxian; Wang, Lirong; Yan, Chao; Wu, Yicheng; Lin, Xuechun; Yao, Jianquan

    2014-06-01

    Third harmonic generation experiments were performed on a type-I phase-matching La2CaB10O19 crystal cut at θ=49.4° and φ=0.0° with dimensions of 4.0  mm×4.0  mm×17.6  mm. A 1064 nm laser with a maximum average power of 35.2 W was employed as the fundamental light source, which has a pulse width of 10 picoseconds and a pulse repetition rate of 80 MHz. A type-I noncritical phase-matching LBO crystal was used to generate 532 nm lasers. By investigating a series of focusing lens combinations, a picosecond 355 nm laser of 5.3 W was obtained, which is the highest power of picosecond 355 nm laser based on a La2CaB10O19 crystal so far. The total conversion efficiency from 1064 to 355 nm was up to 15.1%. PMID:24876039

  4. The growth of 122 and 11 iron-based superconductor single crystals and the influence of doping

    International Nuclear Information System (INIS)

    This review focuses on the various single crystal growth techniques applied to the new class of high temperature superconductors—iron-based layered pnictides, such as the parent compounds AFe2As2 (A = Ba, Sr, Ca) (122), hole-doped A1 − xK xFe2As2, electron/hole-doped AFe2 − xM xAs2 (M = Co, Ni, Mn, Cr), isovalently doped AFe2As2 − xP x, the chalcogenides A xFe2 − ySe2(A = K, Rb, Cs) (122), and Fe1 − δTe1 − xSe x (11). Detailed single crystal growth methods (fluxes, Bridgman, floating zone(FZ)), the associated procedures, and their impact on crystal size and quality are presented. We also discuss the influence of doping on the structure, and the electric, magnetic, and superconducting properties of these compounds by a comparative study of different growth methods. (topical review)

  5. An efficient all-optical gate based on photonic crystals cavities and applications

    OpenAIRE

    Combrié, Sylvain; Martin, Aude; Moille, Gregory; Lehoucq, Gaëlle; De Rossi, Alfredo; Reithmaier, Johann-Peter; Bramerie, Laurent; Gay, Mathilde

    2014-01-01

    International audience We use two coupled photonic crystal cavities to build an all-optical gate. The control and the modulated signal are separated spectrally by about 10 nm. This device was uperated at a rate ranging from 1 to 10 GHz with maximum coupled average power of less than 1 mW in the control signal, which translates to about 100 fJ per control pulse .

  6. Flat-top Drop Filter based on a Single Topology Optimized Photonic Crystal Cavity

    DEFF Research Database (Denmark)

    Frandsen, Lars Hagedorn; Elesin, Yuriy; Guan, Xiaowei;

    2015-01-01

    Outperforming conventional design concepts, a flat-top drop filter has been designed byapplying 3D topology optimization to a single waveguide-coupled L3 photonic crystal cavity.Measurements on the design fabricated in silicon-on-insulator material reveal that the pass-band ofthe drop channel...... is flat within 0.44 dB over a wavelength range of 9.7 nm with an insertion losslower than 0.85 dB....

  7. Modified Photoluminescence by Silicon-Based One-Dimensional Photonic Crystal Microcavities

    Institute of Scientific and Technical Information of China (English)

    CHEN San; QIAN Bo; WEI Jun-Wei; CHEN Kun-Ji; XU Jun; LI Wei; HUANG Xin-Fan

    2005-01-01

    @@ Photoluminescence (PL) from one-dimensional photonic band structures is investigated. The doped photonic crystal with microcavities are fabricated by using alternating hydrogenated amorphous silicon nitride (a-SiNx :H/aSiNy:H) layers in a plasma enhanced chemical vapour deposition (PECVD) chamber. It is observed that microcavities strongly modify the PL spectra from active hydrogenated amorphous silicon nitride (a-SiNz :H) thin film.By comparison, the wide emission band width 208nm is strongly narrowed to 11 nm, and the resonant enhancement of the peak PL intensity is about two orders of magnitude with respect to the emission of the λ/2-thick layer of a-SiNz:H. A linewidth of △λ = 11 nm and a quality factor of Q = 69 are achieved in our one-dimensional a-SiNz photonic crystal microcavities. Measurements of transmittance spectra of the as-grown samples show that the transmittance resonant peak of a cavity mode at 710 nm is introduced into the band gap of one-dimensional photonic crystal distributed Bragg reflector (DBR), which further verifies the microcavity effects.

  8. Coronagraph Focal-Plane Phase Masks Based on Photonic Crystal Technology: Recent Progress and Observational Strategy

    Science.gov (United States)

    Murakami, Naoshi; Nishikawa, Jun; Sakamoto, Moritsugu; Ise, Akitoshi; Oka, Kazuhiko; Baba, Naoshi; Murakami, Hiroshi; Tamura, Motohide; Traub, Wesley A.; Mawet, Dimitri; Moody, Dwight C.; Kern, Brian D.; Trauger, John T.; Serabyn, Eugene; Hamaguchi, Shoki; Oshiyama, Fumika

    2012-01-01

    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.

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

    CERN Document Server

    Pouriayevali, Habib

    2016-01-01

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

  10. Synthesis, Crystal Structure and Photocatalytic Properties of a Supramolecular Assembly Based on Keggin Polyoxotungstate

    Institute of Scientific and Technical Information of China (English)

    CHEN Shun-Yu; CHEN Xin-Qin; LIN Shen

    2012-01-01

    A new supramolecular compound (4,4'-bipyH)4[SiW12O40](4,4'-bipy) (4,4'-bipy = 4,4'-bipyridine) was synthesized hydrothermally and characterized by single-crystal X-ray diffraction and IR spectrum. The crystallography analysis for the title compound reveals that the crystal crystallizes in monoclinic, space group C2/m with a = 22.2767(12), b = 21.1879(11), c = 15.6942(8) A, β = 97.068(3)°, V = 7351.3(7) A3, Cs0H44N10040SiW12, Mr = 3659.24, Z = 4, Dc = 3.306 g/cm3, F(000) = 6544, GOOF = 1.137, R = 0.0577 and wR = 0.1579. The title compound consists of a discrete Keggin-type [SiWl2O40]4- anion, one 4,4'-bipy and four protonated (4,4'-bipyH)+ cations. The [SiWl2O40]4- anion and protonated 4,4'-bipy are connected to form a supramolecular structure by hydrogen bonds. Meanwhile, the title compound exhibits good photocatalytic activity for color degradation of Rhodamine-B dye solution under visible-light irradiation.

  11. Fluorinated Epoxy Resins-based Sorbent Coating Materials for Quartz Piezoelectric Crystal Detector

    Directory of Open Access Journals (Sweden)

    D. C Gupta

    2004-04-01

    Full Text Available Fluorinated epoxy resins were synthesised and evaluated as sorbent coating materials for the detection of organophosphorus compounds using quartz piezoelectric crystal detector. These resins were prepared by reacting excess of epichlorohydrin with each of or in combination of fluorinated diols, ie, a, a, a', a' tetrakis (trifluoromethyl 1,3 benzene dimethanol (TTFMBD, 4,4'bis-2-hydroxy hexafluoro isopropyl biphenyl (BHHFIBP, 4,4'dihydroxyocta fluorodiphenyl (DHOFDP and 2,2,3,3,4,4 hexafluoro 1,5 pentanediol (HFPD in the presence of sodium hydroxide at reflux temperature. These polymers were extracted in organic solvents and dried. Each of these fluoroepoxy resins were coated over quartz piezoelectric crystal by solution-casting method and tested using dimethylmethyl phosphonate (DMMP as model compound. Change in the  frequency (AF of quartz piezoelectric crystal oscillator was recorded. Sensitive and potential fluorinated epoxy resins, ie, diglycidylethers (DGE of HFPD-TTFMBD (in the molar ratio 6:4 and DGE (HFPD-BHHFIBP in the molar ratio 4:6 were characterised by viscosity, number average molecular weight (Mn, epoxy equivalent, infrared spectroscopy, and thermal stability.

  12. Anisotropic stress rupture properties of the nickel-base single crystal superalloy SRR99

    International Nuclear Information System (INIS)

    The influence of orientation on the stress rupture properties of a single crystal superalloy SRR99 was investigated at temperatures of 760 and 1040 deg. C. It is found that the creep anisotropic behaviour is pronounced at the lower temperature of 760 deg. C and the stress rupture life ranks in the order [0 0 1] > [1 1 1] > [0 1 1]. Despite the anisotropy of stress rupture life is evidently reduced at the higher temperature, the [1 1 1] orientation exhibits the longest life. At 760 deg. C, EBSD (electron back scattered diffraction) was adopted to measure the lattice rotation and the deduced results indicate that the dominant slip systems are {1 1 1} during stress rupture test. At 1040 deg. C, the ranking order of the stress rupture life is [1 1 1] > [0 0 1] > [0 1 1] and the single crystal close to [0 1 1] orientation still shows the poorest life. In the [0 0 1] and [1 1 1] samples, regular γ' raft structure is formed compared with [0 1 1] samples. Further observations made by TEM investigations reveal the underlying deformation mechanisms for crystals with orientations near [0 0 1], [0 1 1] and [1 1 1] under two test conditions.

  13. Liquid crystal devices with continuous phase variation based on high-permittivity thin films

    Science.gov (United States)

    Willekens, Oliver; Neyts, Kristiaan; Beeckman, Jeroen

    2016-03-01

    Most liquid crystal devices use transparent conductive electrodes such as indium tin oxide (ITO) to apply a potential difference in order to achieve electro-optic switching. As an alternative, we study a device with narrow metallic electrodes in combination with dielectric layers with large dielectric permittivity. In this approach the applied voltage can be a continuous function of the lateral distance from the electrode line. Simulations for a one-dimensional beam-steering device show that the switching of the liquid crystal (LC) director depends indeed on the distance from the addressing electrodes and on the value of the relative permittivity. We show that in a device with electrodes spaced 60 µm apart, the LC director halfway between the electrodes shows a considerable reorientation, when a dielectric layer with permittivity of Epsilonr = 550 is used, whereas no reorientation is observed for the uncoated reference sample at the same voltage. An added advantage is that the proposed configuration only contains dielectric materials, without resistive losses, which means that almost no heat is dissipated. This indicates that this technology could be used in low-power LC devices. The results show that using dielectric thin films with high relative permittivity in liquid crystal devices could form a cost-efficient and low-power alternative to many LC technologies where a gradient electric field is desirable.

  14. Crystal Meth

    Science.gov (United States)

    ... for: Navigation Home / Stories of Hope / Crystal meth Crystal meth Story Of Hope By giovanni January 3rd, ... about my drug addiction having to deal with Crystal meth. I am now in recovery and fighting ...

  15. Synthesis, growth, optical and DFT calculation of 2-naphthol derived Mannich base organic non linear optical single crystal for frequency conversion applications

    Science.gov (United States)

    Raj, A. Dennis; Jeeva, M.; Shankar, M.; Purusothaman, R.; Prabhu, G. Venkatesa; Potheher, I. Vetha

    2016-11-01

    2-naphthol derived Mannich base 1-((4-methylpiperazin-1-yl) (phenyl) methyl) naphthalen-2-ol (MPN) - a nonlinear optical single crystal was synthesized and successfully grown by slow evaporation technique at room temperature. The molecular structure was confirmed by single crystal XRD, FT-IR, 1H NMR and 13C NMR spectral studies. The single crystal X-ray diffraction analysis reveals that the crystal belongs to orthorhombic crystal system with non-centrosymmetric space group Pna21. The chemical shift of 5.34 ppm (singlet methine CH proton) in 1H NMR and signal for the CH carbon around δ70.169 ppm in 13C NMR confirms the formation of the title compound. The crystal growth pattern and dislocations of crystal are analyzed using chemical etching technique. UV cut off wavelength of the material was found to be 212 nm. The second harmonic generation (SHG) of MPN was determined from Kurtz Perry powder technique and the efficiency is almost equal to that of standard KDP crystal. The laser damage threshold was measured by passing Nd: YAG laser beam through the sample and it was found to be 1.1974 GW/cm2. The material was thermally stable up to 142 °C. The relationship between the molecular structure and the optical properties was also studied from quantum chemical calculations using Density Functional Theory (DFT) and reported for the first time.

  16. Effect of epicuticular wax crystals on the localization of artificially deposited sub-micron carbon-based aerosols on needles of Cryptomeria japonica.

    Science.gov (United States)

    Nakaba, Satoshi; Yamane, Kenichi; Fukahori, Mie; Nugroho, Widyanto Dwi; Yamaguchi, Masahiro; Kuroda, Katsushi; Sano, Yuzou; Wuled Lenggoro, I; Izuta, Takeshi; Funada, Ryo

    2016-09-01

    Elucidation of the mechanism of adsorption of particles suspended in the gas-phase (aerosol) to the outer surfaces of leaves provides useful information for understanding the mechanisms of the effect of aerosol particles on the growth and physiological functions of trees. In the present study, we examined the localization of artificially deposited sub-micron-sized carbon-based particles on the surfaces of needles of Cryptomeria japonica, a typical Japanese coniferous tree species, by field-emission scanning electron microscopy. The clusters (aggregates) of carbon-based particles were deposited on the needle surface regions where epicuticular wax crystals were sparsely distributed. By contrast, no clusters of the particles were found on the needle surface regions with dense distribution of epicuticular wax crystals. Number of clusters of carbon-based particles per unit area showed statistically significant differences between regions with sparse epicuticular wax crystals and those with dense epicuticular wax crystals. These results suggest that epicuticular wax crystals affect distribution of carbon-based particles on needles. Therefore, densely distributed epicuticular wax crystals might prevent the deposition of sub-micron-sized carbon-based particles on the surfaces of needles of Cryptomeria japonica to retain the function of stomata.

  17. Visualization of soft tissues by highly sensitive X-ray crystal analyzer-based multi diffraction enhanced imaging

    Science.gov (United States)

    Wu, Yanlin; Sunaguchi, Naoki; Lin, Xiaojie; Wang, Yongting; Yuasa, Tetsuya; Hirano, Keiichi; Hyodo, Kazuyuki

    2015-09-01

    In this paper, we propose a novel multi diffraction enhanced imaging (MDEI) technique to improve contrast resolution owning to the sharp rise of the reflectivity curve and high contrast-to-noise ratio (CNR). MDEI is derived from the diffraction enhanced imaging (DEI) technique. Here, DEI and MDEI phase contrast tomograms are compared. The results show that MDEI offers higher contrast resolution, while DEI has higher spatial resolution. This study provided indications for developments and applications of X-ray crystal analyzer-based imaging to obtain a higher contrast resolution.

  18. An Electronic Nose Based on Coated Piezoelectric Quartz Crystals to Certify Ewes’ Cheese and to Discriminate between Cheese Varieties

    Directory of Open Access Journals (Sweden)

    Maria Teresa S. R. Gomes

    2012-02-01

    Full Text Available An electronic nose based on coated piezoelectric quartz crystals was used to distinguish cheese made from ewes’ milk, and to distinguish cheese varieties. Two sensors coated with Nafion and Carbowax could certify half the ewes’ cheese samples, exclude 32 cheeses made from cow’s milk and to classify half of the ewes’ cheese samples as possibly authentic. Two other sensors, coated with polyvinylpyrrolidone and triethanolamine clearly distinguished between Flamengo, Brie, Gruyère and Mozzarella cheeses. Brie cheeses were further separated according to their origin, and Mozzarella grated cheese also appeared clearly separated from non-grated Mozzarella.

  19. Surface Anchoring Stabilized High Strength Disclinations in Smectic C Phase of a Schiff-base Liquid Crystal

    Institute of Scientific and Technical Information of China (English)

    ZHANG Qi-Zhen张其震; CUI Li崔利; YIN Xiao-Ying殷晓颖

    2004-01-01

    The observation of disclination cores of high strength S= -2, -3, -4, -5, -6, -7, -8 in a smectic C phase of Schiff-base type liquid crystal (LC) is reported. The results of polarizing optical microscope (POM), differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) prove that the sample exhibits smectic C phase. It is suggested that the formation of the high strength disclination is mainly ascribed to the stronger anchoring of LC molecules on the substrate due to the formation of hydrogen bonds between the pendent hydroxyl of the LC molecule and the substrate.

  20. Visualization of soft tissues by highly sensitive X-ray crystal analyzer-based multi diffraction enhanced imaging

    International Nuclear Information System (INIS)

    In this paper, we propose a novel multi diffraction enhanced imaging (MDEI) technique to improve contrast resolution owning to the sharp rise of the reflectivity curve and high contrast-to-noise ratio (CNR). MDEI is derived from the diffraction enhanced imaging (DEI) technique. Here, DEI and MDEI phase contrast tomograms are compared. The results show that MDEI offers higher contrast resolution, while DEI has higher spatial resolution. This study provided indications for developments and applications of X-ray crystal analyzer-based imaging to obtain a higher contrast resolution. (author)

  1. Design and Simulation of Butterworth Filter based on One-Dimensional Photonic Crystals using Transfer Matrix Method

    Directory of Open Access Journals (Sweden)

    Reza Khodadadi

    2014-03-01

    Full Text Available These in the present paper designs and simulates a FIR using one- dimensional Photonic Crystals structure based on materials, including Silicon (Si and Germanium (Ge to put into operation in optical communication systems. In this process, it examines the effect of the bandwidth of the optical transmission system using the operation of Butterworth filter and through Transfer Matrix Method (TMM, the case of diffraction of light and Defect. It also considers the changes in frequency characteristics of the system due to an increase in the width of the layers and Defects

  2. Asymmetric Mach-Zehnder filter based on self-collimation phenomenon in two-dimensional photonic crystals.

    Science.gov (United States)

    Kim, Teun-Teun; Lee, Sun-Goo; Park, Hae Yong; Kim, Jae-Eun; Kee, Chul-Sik

    2010-03-15

    A two-dimensional photonic crystal asymmetric Mach-Zehnder filter (AMZF) based on the self-collimation effect is studied by numerical simulations and experimental measurements in microwave region. A self-collimated beam is effectively controlled by employing line-defect beam splitters and mirrors. The measured transmission spectra at the two output ports of the AMZF sinusoidally oscillate with the phase difference of pi in the self-collimation frequency range. Position of the transmission peaks and dips can be controlled by varying the size of the defect rod of perfect mirrors, and therefore this AMZF can be used as a tunable power filter. PMID:20389553

  3. An Acetylcholinesterase Antibody-Based Quartz Crystal Microbalance for the Rapid Identification of Spinal Ventral and Dorsal Roots

    OpenAIRE

    Tao Sui; Yingbin Ge; Wujun Liu; Zhao, Zongbao K.; Ning Zhang; Xiaojian Cao

    2013-01-01

    Differences in the levels of acetylcholinesterase (AChE) in ventral and dorsal spinal roots can be used to differentiate the spinal nerves. Although many methods are available to assay AChE, a rapid and sensitive method has not been previously developed. Here, we describe an antibody-based quartz crystal microbalance (QCM) assay and its application for the quantification of AChE in the solutions of ventral and dorsal spinal roots. The frequency variation of the QCM device corresponds to the l...

  4. Surface recrystallization of a Ni_3Al based single crystal superalloy at different annealing temperatures and blasting pressure

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    The effects of annealing temperature and grit blasting pressure on the recrystallization behavior of a Ni3Al based single crystal superalloy were studied in this work. The results show that the precipitation of the Y-NiMo phase occurs at 900 and 1000 °C, which precedes recrystallization. The initial recrystallization temperature was between 1000 and 1100 °C. Cellular recrystallization was formed at 1100 and 1200 °C, which consisted of large columnar γ′ and fine γ + γ′. The dendrite arm closed to the interde...

  5. Low cycle fatigue of the single-crystal nickel-base superalloy CMSX-4. Anistropy and effect of creep damage

    Energy Technology Data Exchange (ETDEWEB)

    Klingelhoeffer, Hellmuth [Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin (Germany). Lab. of Mechanical Behaviour of Metals and Metal Matrix Composites; Epishin, Alexander; Link, Thomas [Technical Univ. Berlin (Germany). Dept. of Metallic Materials

    2009-07-01

    Low cycle fatigue of the single-crystal nickel-base superalloy CMSX-4 was investigated in the temperature range 700-950 C under strain controlled cyclic loading. The points of interest were the crystallographic anisotropy of low cycle fatigue behaviour and the effect of creep damage on low cycle fatigue life. For the testing conditions used the low cycle fatigue life of CMSX-4 is strongly orientation dependent as well as very sensitive to the formation of rafted {gamma}/{gamma}'-microstructure. (orig.)

  6. Synthesis, crystal structure and properties of inorganic-organic hybrid polymers based on 8-hydroxylquinoline-5-sulfonic acid

    Institute of Scientific and Technical Information of China (English)

    WANG Ying; XUE Ming; XU JiaNing; ZHU GuangShan; QIU ShiLun

    2009-01-01

    Two new inorganic-organic hybrid polymers, Mn(QS)(H_2O) (1) and Co(QS)(H_2O)2 (2) (H2QS=8-hydroxylquinoline-5-sulfonic acid), based on 8-hydroxylquinoline-5-sulfonate ligand, have been synthesized under solvothermal conditions and their structures were solved by single-crystal X-ray diffraction analysis. Compound 1 is a three-dimensional open framework with rutile topology structure, and compound 2 is a three-dimensional supramolecular structure. These compounds were characterized by powder XRD, infrared spectroscopy, thermogravimetric analysis, fluorescence properties and magnetism properties.

  7. Synthesis,crystal structure and properties of inorganic-organic hybrid polymers based on 8-hydroxylquinoline-5-sulfonic acid

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Two new inorganic-organic hybrid polymers, Mn(QS)(H2O) (1) and Co(QS)(H2O)2 (2) (H2QS=8-hydroxyl-quinoline-5-sulfonic acid), based on 8-hydroxylquinoline-5-sulfonate ligand, have been synthesized under solvothermal conditions and their structures were solved by single-crystal X-ray diffraction analysis. Compound 1 is a three-dimensional open framework with rutile topology structure, and compound 2 is a three-dimensional supramolecular structure. These compounds were characterized by powder XRD, infrared spectroscopy, thermogravimetric analysis, fluorescence properties and magnetism properties.

  8. Preparation, glass forming ability, crystallization and deformation of (zirconium, hafnium)-copper-nickel-aluminum-titanium-based bulk metallic glasses

    Science.gov (United States)

    Gu, Xiaofeng

    Multicomponent Zr-based bulk metallic glasses are the most promising metallic glass forming systems. They exhibit great glass forming ability and fascinating mechanical properties, and thus are considered as potential structural materials. One potential application is that they could be replacements of the depleted uranium for making kinetic energy armor-piercing projectiles, but the density of existing Zr-based alloys is too low for this application. Based on the chemical and crystallographic similarities between Zr and Hf, we have developed two series of bulk metallic glasses with compositions of (HfxZr1-x) 52.5Cu17.9Ni14.6Al10Ti5 and (HfxZr1-x) 57Cu20Ni8Al10Ti5 ( x = 0--1) by gradually replacing Zr by Hf. Remarkably increased density and improved mechanical properties have been achieved in these alloys. In these glasses, Hf and Zr play an interchangeable role in determining the short range order. Although the glass forming ability decreases continuously with Hf addition, most of these alloys remain bulk glass-forming. Recently, nanocomposites produced from bulk metallic glasses have attracted wide attention due to improved mechanical properties. However, their crystalline microstructure (the grain size and the crystalline volume fraction) has to be optimized. We have investigated crystallization of (Zr, Hf)-based bulk metallic glasses, including the composition dependence of crystallization paths and crystallization mechanisms. Our results indicate that the formation of high number density nanocomposites from bulk metallic glasses can be attributed to easy nucleation and slowing-down growth processes, while the multistage crystallization behavior makes it more convenient to control the microstructure evolution. Metallic glasses are known to exhibit unique plastic deformation behavior. At low temperature and high stress, plastic flow is localized in narrow shear bands. Macroscopic investigations of shear bands (e.g., chemical etching) suggest that the internal

  9. Megawatt peak power, 1 kHz, 266 nm sub nanosecond laser source based on single-crystal fiber amplifier

    Science.gov (United States)

    Deyra, Loïc; Martial, Igor; Balembois, François; Diderjean, Julien; Georges, Patrick

    2013-06-01

    We report the realization of a UV source based on the fourth harmonic generation with LBO/BBO of a Nd:YAG passively Q-switched oscillator amplified in a single-crystal fiber. With careful optimization of the nonlinear components and parameters, we obtain 530 mW average power at 266 nm with pulses of 540 ps at the repetition rate of 1 kHz, which represents a 22.7 % total conversion efficiency from IR to UV and nearly 1 MW peak power. The beam quality M 2 is measured to be below 2.

  10. Megawatt peak power, 1 kHz, 266 nm sub nanosecond laser source based on single-crystal fiber amplifier

    OpenAIRE

    Deyra, Loïc; Martial, Igor; Julien, Didierjean; Balembois, François; Georges, Patrick

    2013-01-01

    International audience We report the realization of a UV source based on the fourth harmonic generation with LBO/BBO of a Nd:YAG passively Q:switched oscillator amplified in a single-crystal fiber. With careful optimization of the nonlinear components and parameters, we obtain 530 mW average power at 266 nm with pulses of 540 ps at the repetition rate of 1 kHz, which represents a 22.7% total conversion efficiency from IR to UV and nearly 1 MW peak power. The beam quality M² is measured to ...

  11. The single-longitudinal-mode operation of a ridge waveguide laser based on two-dimensional photonic crystals

    Institute of Scientific and Technical Information of China (English)

    Wang Hua-Yong; Xu Xing-Sheng

    2013-01-01

    An electrically driven,single-longitudinal-mode GaAs based photonic crystal (PC) ridge waveguide (RWG) laser emitting at around 850 nm is demonstrated.The single-longitudinal-mode lasing characteristic is achieved by introducing the PC to the RWG laser.The triangle PC is etched on both sides of the ridge by photolithography and inductive coupled plasma (ICP) etching.The lasing spectra of the RWG lasers with and without the PC are studied,and the result shows that the PC purifies the longitudinal mode.The power per facet versus current and current-voltage characteristics have also been studied and compared.

  12. Synthesis, characterization, crystal structure determination and catalytic activity in epoxidation reaction of two new oxidovanadium(IV) Schiff base complexes

    Science.gov (United States)

    Tahmasebi, Vida; Grivani, Gholamhossein; Bruno, Giuseppe

    2016-11-01

    The five coordinated vanadium(IV) Schiff base complexes of VOL1 (1) and VOL2 (2), HL1 = 2-{(E)-[2-bromoethyl)imino]methyl}-2- naphthol, HL2 = 2-{(E)-[2-chloroethyl)imino]methyl}-2- naphthol, have been synthesized and they were characterized by using single-crystal X-ray crystallography, elemental analysis (CHN) and FT-IR spectroscopy. Crystal structure determination of these complexes shows that the Schiff base ligands (L1 and L2) act as bidentate ligands with two phenolato oxygen atoms and two imine nitrogen atoms in the trans geometry. The coordination geometry around the vanadium(IV) is distorted square pyramidal in which vanadium(IV) is coordinated by two nitrogen and two oxygen atoms of two independent ligands in the basal plane and by one oxygen atom in the apical position. The catalytic activity of the Schiff base complexes of 1 and 2 in the epoxidation of alkenes were investigated using different reaction parameters such as solvent effect, oxidant, alkene/oxidant ratio and the catalyst amount. The results showed that in the presence of TBHP as oxidant in 1: 4 and 1:3 ratio of the cyclooctene/oxidant ratio, high epoxide yield was obtained for 1 (76%) and 2 (80%) with TON(= mole of substrate/mole of catalyst) of 27 and 28.5, respectively, in epoxidation of cyclooctene.

  13. A dislocation density based crystal plasticity finite element model: Application to a two-phase polycrystalline HCP/BCC composites

    Science.gov (United States)

    Ardeljan, Milan; Beyerlein, Irene J.; Knezevic, Marko

    2014-05-01

    We present a multiscale model for anisotropic, elasto-plastic, rate- and temperature-sensitive deformation of polycrystalline aggregates to large plastic strains. The model accounts for a dislocation-based hardening law for multiple slip modes and links a single-crystal to a polycrystalline response using a crystal plasticity finite element based homogenization. It is capable of predicting local stress and strain fields based on evolving microstructure including the explicit evolution of dislocation density and crystallographic grain reorientation. We apply the model to simulate monotonic mechanical response of a hexagonal close-packed metal, zirconium (Zr), and a body-centered cubic metal, niobium (Nb), and study the texture evolution and deformation mechanisms in a two-phase Zr/Nb layered composite under severe plastic deformation. The model predicts well the texture in both co-deforming phases to very large plastic strains. In addition, it offers insights into the active slip systems underlying texture evolution, indicating that the observed textures develop by a combination of prismatic, pyramidal, and anomalous basal slip in Zr and primarily {110} slip and secondly {112} slip in Nb.

  14. A highly sensitive quartz crystal microbalance immunosensor based on magnetic bead-supported bienzymes catalyzed mass enhancement strategy.

    Science.gov (United States)

    Akter, Rashida; Rhee, Choong Kyun; Rahman, Md Aminur

    2015-04-15

    A highly sensitive quartz crystal microbalance (QCM) immunosensor based on magnetic bead-supported bienzyme catalyzed mass enhanced strategy was developed for the detection of human immunoglobulin G (hIgG) protein. The high sensitive detection was achieved by increasing the deposited mass on the QCM crystal through the enhanced precipitation of 4-chloro-1-naphthol (CN) using higher amounts of horseradish peroxidase (HRP) and glucose oxidase (GOx) bienzymes attached on the magnetic beads (MB). The protein A (PA) and capture antibody (monoclonal anti-human IgG antibody produced in mouse, Ab1)-based QCM probe and the detection antibody (anti-human IgG antibody produced in goat, Ab2)-based MB/HRP/GOx bienzymatic bioconjugates were characterized using scanning electron microscope, transmission electron microscope, cyclic voltammetry, and electrochemical impedance spectroscopy techniques. Under the optimized experimental condition, the linear range and the detection limit of hIgG immunosensor were determined to be 5.0pg/mL-20.0ng/mL and 5.0±0.18pg/mL, respectively. The applicability of the present hIgG immunosensor was examined in hIgG spiked human serum samples and excellent recoveries of hIgG were obtained. PMID:25506902

  15. Compact and high-power broadband terahertz source based on femtosecond photonic crystal fiber amplifier

    Institute of Scientific and Technical Information of China (English)

    Feng Liu; Lu Chai; Qirong Xing; Chingyue Wang; Weili Zhang; Xiaokun Hu; Jiang Li; Changlei Wang; Yi Li; Yanfeng Li; YoujianSong; Bowen Liu; Minglie Hu

    2011-01-01

    Terahertz (THz) waves,generally defined in the 0.1-10 THz range are finding growing applications in various important fields[1-4] such as imaging,food and pharmaceutical quality coutrol,security screening,and standoff detection of bio-threat species,among which THz timedomain spectroscopy (THz-TDS)[5] is particularly appealing.However,the low conversion efficiency and low power of typical broadband THz sources severely hinder the utility and realization of the full potential of THzTDS.Recently,there have been efforts to generate THz pulses using compact pump sources in fiber format[6,7].%We present a review of the development of a compact and high-power broadband terahertz (THz) source optically excited by a femtosecond photonic crystal fiber (PCF) amplifier. The large mode area of the PCF and the stretcher-free configuration make the pump source compact and very efficient. Broadband THz pulseg of 150 μW extending from 0.1 to 3.5 TH2 are generated from a 3-mm-thick GaP crystal through optical rectification of 12-W pump pulses with duration of 66 & and a repetition rate of 52 MHz. A strong saturation effect is observed, which is attributed to pump pulse absorption; a Z-scan measurement shows that three-photon absorption dominates the nonlinear absorption when the crystal is pumped by femtosecond pulses at 1040 run. A further scale-up of the THz source power is expected to find important applications in THz nonlinear optics and nonlinear THz spectroscope

  16. Design and development of a solution growth system based on constant temperature and constant supersaturation technique for rapid growth of KD P Crystals

    International Nuclear Information System (INIS)

    A one-vessel crystal growth system has been built to grow KD P crystals of up to 10 cm in length. The process is based on transfer of saturated solution under constant temperature-constant supersaturation. Ca ry 17 D X spectrophotometer transmission spectra from (100) planes of the grown crystals show 89% transmission in the visible region. The system provides a reduction in capping time and growth rate of 25 mm/day for the first day and 1.5 mm/day for the 7th day

  17. Converter of laser beams with circular polarization to cylindrical vector beams based on anisotropic crystals

    Science.gov (United States)

    Paranin, Vyacheslav D.; Karpeev, Sergey V.; Kazanskiy, Nikolay L.; Krasnov, Andrey P.

    2016-03-01

    The optical system for converting laser beams with circular polarization to cylindrical vector beams on the basis of anisotropic crystals has been developed. The experimental research of beam formation quality has been carried out on the both polarization and structural characteristics. The research showed differences in the formation of the azimuthal and radial polarizations for Gaussian modes and Bessel beams. The boundaries of changes of the optical system parameters to form different types of polarizations with different amplitude and phase distributions have been identified.

  18. Flat super-continuum generation based on normal dispersion nonlinear photonic crystal fibre

    DEFF Research Database (Denmark)

    Chow, K.K.; Takushima, Y.; Lin, C.;

    2006-01-01

    Flat super-continuum generation spanning over the whole telecommunication band using a passively modelocked fibre laser source at 1550 nm together with a dispersion-flattened nonlinear photoinc crystal fibre is demonstrated. Since the pulses propagate in the normal dispersion regime of the fibre...... only, linear frequency chirp is induced by self-phase modulation which leads to a flat super-continuum. By launching the compressed 170 fs modelocked pulses with an average power of 10 mW into the fibre, super-continuum over 185 nm with less than 5 dB fluctuation is obtained from the all...

  19. Logical operation of one-dimensional photonic crystal based on series and parallel connection

    CERN Document Server

    Wu, Xiang-Yao; Liu, Xiao-Jing; Meng, Xiang-Dong; Liang, Yu; Li, Hong; Zhang, Si-Qi

    2015-01-01

    In this paper, we have proposed the compound structure of one-dimensional photonic crystal (PC), which includes series connection and parallel connection PC. We have studied the transmission characteristics of series connection and parallel connection PC, and obtained some new results. In addition, we have proved the series connection one-dimensional PC can realize the logical AND operation, and the parallel connection one-dimensional PC can realize the logical OR operation. The compound structure of one-dimensional PC can design more new type structure optical devices, and will provide the basic for designing quantum computer.

  20. Broadening of Omnidirectional Photonic Band Gap in Graphene Based one Dimensional Photonic Crystals

    Directory of Open Access Journals (Sweden)

    Neetika Arora

    2015-09-01

    Full Text Available A simple design of one dimensional gradual stacked photonic crystal has been proposed. This structure exhibits a periodic array of alternate layers of Graphene and Silica. These are the materials of low and high refractive indices respectively. Here the structure considered has three stacks .Each stack has five alternate layers of Graphene and silica. The transfer matrix method has been used for numerical computation. In this paper, such a structure has wider reflection bands in comparison to a conventional dielectric PC structure and structure with Sio2 and Si layers for a constant gradual constant ϒ at different incident angle.